Working during pregnancy

INTRODUCTION — Worldwide, women are working during all trimesters of pregnancy for reasons including career pursuit and fulfillment, financial necessity, preservation of insurance, career advancement, and preservation of postpartum leave time. Working pregnant women often request advice and assistance from their clinicians to manage challenges that occur while being pregnant at work. This topic will review issues including the impact of pregnancy on work, the impact of work on pregnancy, workplace exposure, leave time and discrimination, and requesting accommodations to enable pregnant women to continue working.

Topics related to occupational risks and exposure are presented separately.

●(See "Overview of occupational and environmental risks to reproduction in females".)

●(See "Occupational and environmental risks to reproduction in females: Specific exposures and impact".)

●(See "Overview of occupational and environmental health".)

In this topic, when discussing study results, we will use the terms "women" or "patients" as they are used in the studies presented. However, we recognize that not all persons capable of pregnancy identify as women, and we encourage the reader to consider the specific counseling and treatment needs of transgender and gender non-binary individuals.

PREVALENCE — As the number of women in the workforce has risen, so has the number of women working while pregnant. Globally, 67 percent of women in developed countries between the ages of 15 and 64 years old were employed in 2014 [1].

Specific to the United States:

●In 2019, 72.3 percent of women with children under age 18 were in the labor force (defined as either employed or seeking work), up from approximately 30 percent in 1950 [2].

●In 2015, the Pew Research Center reported [3]:

•Fifty-six percent of women worked full time during their first pregnancy.

•Eighty-two percent of nulliparous women continued to work to within the month before they were due.

•Most (73 percent) returned to work within six months after delivery.

For comparison, in the early 1960s, only 44 percent worked during pregnancy, and 65 percent of them stopped work more than a month prior to delivery.

IMPACT

Pregnancy on work performance — Pregnancy is associated with a wide variety of physical, functional, and emotional changes. While many women work while pregnant without any interference from pregnancy-related changes, problems of nausea and vomiting, pain, and fatigue can negatively impact a woman's work performance. (See "Clinical manifestations and diagnosis of early pregnancy".)

●Nausea and/or vomiting – Nausea and/or vomiting can be provoked by workplace odors or restrictions around eating [4]. These problems can usually be managed with hydration, snacking as needed, taking a brief break, medication, and scheduling the most demanding work for times when the individual tends to feel less nauseous, if possible. One retrospective survey study suggested an inverse relationship between first-trimester level of nausea [5], physical activity, and standing. Clinicians may need to request accommodations for their patients to allow for such non-medical interventions. In cases of severe vomiting requiring intensive outpatient intravenous or hospital-based therapy, a short-term absence from work can be necessary. (See "Nausea and vomiting of pregnancy: Treatment and outcome".)

●Fatigue – In an interview study of first-time pregnant working women, the dominant theme was described as "living on the edge of being overstretched" [6]. Being exhausted from adapting to professional life while pregnant was a major contributor to this theme.

●Discomfort and pain – By the end of the second trimester and continuing through term, physical and physiologic changes can bring on heartburn, back pain, joint pain, varicose veins, hemorrhoids, and physical discomfort from the enlarging uterus. Ideally, the individual and their employer will be able to make reasonable adjustments to deal with these discomforts in the workplace. Simple precautions that can help reduce excessive fatigue, discomfort, and potentially reduce the risk of pregnancy complications include modifying shift times and tasks; minimizing lifting, bending, and prolonged standing; using proper lifting techniques; taking regular breaks every few hours and a longer break after five hours; and drinking plenty of fluids [7-13]. However, lost work time and interruptions in workflow can be necessary. (See "Maternal adaptations to pregnancy: Musculoskeletal changes and pain".)

●Cognitive function – Reduced cognitive function during pregnancy is often referred to as "baby brain." One meta-analysis including over 700 pregnant individuals reported that up to 80 percent noted this symptom during pregnancy with forgetfulness being the most common complaint [14]. Compared with control individuals, pregnant individuals report more subjective difficulties with memory, mood, and quality of life [15]. However, such subjective perceptions may not be replicated by objective testing. While numerous changes in specific brain regions in humans occur during pregnancy and persist thereafter, they may have adaptive functions [16]. More data are needed to understand the impact of pregnancy on cognitive function.

Work on pregnancy and child development — Despite data limitations, working while pregnant generally does not appear to negatively impact maternal or fetal health. However, the effect of work on pregnancy outcome is difficult to assess because available data are often contradictory, largely retrospective, and subject to multiple sources of bias, including inadequate adjustment for confounders, recall bias, selective participation, and subjective assessment of exposures. In particular, a potential bias in observational studies of outcomes of pregnant women who work or do not work is the "healthy worker" effect whereby healthier workers are more likely to continue to work and work in more demanding jobs than women with less robust health.

●Pregnancy – Systematic reviews have generally concluded that standard working conditions present little hazard to maternal or child health [17,18]. A woman with an uncomplicated pregnancy who is employed where there are no greater potential hazards than those encountered in routine daily life may continue to work without interruption until the onset of labor. However, the physical demands of the woman's job are evaluated on a case-by-case basis, especially in women who have medical or obstetric disorders that are unstable or associated with impaired placental perfusion (eg, preeclampsia, fetal growth restriction). As an example, studies of the effect of work on a woman's risk of developing hypertension during pregnancy generally report no significant association; however, the risk may depend on the occupational classification [19-21]. While available evidence is inadequate to support a change in occupational responsibilities for prevention of pregnancy-related hypertensive disorders, limited data do support changes in physical activity in the management of some women who develop these disorders. (See 'Selected workplace exposures' below and "Spontaneous preterm birth: Overview of risk factors and prognosis", section on 'Occupational physical activity'.)

●Child development – Assessing the impact of maternal employment on children's development is difficult because of selection bias and missing data (eg, quality of childcare, home environment, maternal sensitivity to the child's needs, paternal factors). While the literature is conflicting, the body of evidence generally reports that if there are any adverse effects of maternal employment on child development, these effects are likely to be small [22-24].

●Impact of socioeconomic status – Women in lower socioeconomic groups may represent an exception to the above information. In a 2014 survey study of 1400 pregnant French workers, women classified as deprived were more likely to encounter occupational hazards, have three or more occupational exposures during a pregnancy, and, for those with three or more occupational exposures, have a preterm delivery when compared with non-deprived women [25,26]. Similarly, in a study from the national Swedish Registry, low levels of job control and high levels of physical demands and job hazards were more common in manual compared with non-manual labor classes. In multivariate analyses, class differences in maternal working conditions explained 14 to 38 percent of low-birth-weight births and 20 to 46 percent of preterm births [27].

●Impact of job type – Some jobs may increase risk of poor pregnancy outcomes, likely through a combination of physical demand, mental stress, fatigue, and work schedule (work duration and shift timing). For example, a survey study reported female surgeons, as compared with female partners of male surgeons, were more likely to experience pregnancy complications (48.3 versus 27.2 percent) or pregnancy loss (42 percent, or more than double that of an age-matched population [28]) in adjusted analysis [29]. Compared with their male surgeon counterparts, female surgeons were more likely to delay childbearing because of surgical training (65 versus 44 percent), have fewer children (mean 1.8 versus 2.3), and use assisted reproductive technology (25 versus 17 percent). While it is not known which component(s) most contributes to these outcomes, the female surgeons who operated more than 12 hours per week during the third trimester had increased risk of major pregnancy complications than those operating fewer than 12 hours, which suggests work duration and/or physicality may play a role and provide an area for modification. Although recall bias is one limitation of survey studies, maternal recall of obstetric complications has been reported to be highly correlated with medical record data [30,31].

WORK CHARACTERISTICS

Hours, shift, and type of work — For women with healthy uncomplicated singleton pregnancies, the Royal College of Physicians (RCP) and the Faculty of Occupational Medicine (FOM) of the United Kingdom concluded that available evidence did not justify imposing mandatory restrictions to working hours, shift work, lifting, standing, and physical work during pregnancy [18]. Challenges to writing such guidelines include lack of data demonstrating a clear cut-off at which work is detrimental to the health of most women and fetuses as well as the reality that some women must continue working while pregnant for economic reasons, regardless of medical advice. Any guidelines must also balance data suggesting that some level of physical activity while pregnant is healthy. Both the Royal College of Obstetricians and Gynaecologists (RCOG) and the American College of Obstetricians and Gynecologists (ACOG) state that physical activity during pregnancy is beneficial to most women, exercise is safe for both mother and fetus, and exercising while pregnant carries little risk [32,33]. In addition, abstaining from work can create hardships that need to be considered and balanced with the anxiety and uncertainty of possible low levels of risk. (See "Exercise during pregnancy and the postpartum period".)

One United States analysis of "occupational physical activity" reported that high activity levels were significantly associated with small for gestational age (SGA) for the highest quartile compared with lowest quartile and were also positively associated with preterm birth [34]. In contrast, analysis of the impact of nonoccupational activity suggests that low physical activity may increase at least preterm birth risk compared to higher levels [35]. While activity during pregnancy is generally encouraged, the point at which extreme activity (such as that imposed by extended work-hours or heavy work) transitions from benefit to harm is less clear. Challenges to understanding the impact of work factors during pregnancy include that data are derived from observational studies, the definition of important outcomes varies by patient, and pregnant individuals interpret and tolerate risk differently. Thus, the physical demands of a pregnant person's job should be considered on a case-by-case basis, especially in those at higher risk of preterm delivery or who have medical or obstetric disorders that are unstable or associated with impaired placental perfusion (eg, preeclampsia, fetal growth restriction).

In one large nationally representative dataset, 31 percent of women reported standing for more than 75 percent of their time at their jobs [36]. A subsequent meta-analysis found prolonged standing to be associated with increased odds of prematurity (OR 1.11, 1.02-1.22) and SGA (OR 1.17, 1.01-1.35) [37].

Concurrent physical and psychological stressors may have a cumulative effect. A Danish cohort study of women expecting one child and who worked 30 or more hours per week found a significant interaction between lifting and psychosocial job strain for SGA and LGA [38]. For each additional 250 kg lifted per day, high-strain women (high demand/low control) had increased odds of giving birth to an LGA child (OR 1.15, 95% CI 1.06-1.26), whereas women with high demand/high control had increased odds of giving birth to an SGA child (OR 1.12, 95% CI 1.03-1.23). In the same study, the adjusted hazard ratio for absence from work increased from 1.3 (1.1 to 1.5) for one exposure to 2.9 (2.5 to 3.3) for four to five exposures compared with no occupational exposure. The occupational exposures included job demands, job control, work posture, work shift, and lifting [39].

Shift and night work schedules — A review of studies assessing the impact of fixed and rotating shift work schedules reported that, while the studies were not conclusive, the evidence suggested that both work schedules were associated with menstrual cycle disturbances and pregnancy loss [40]. However, the effect size was uncertain.

●Night shift work – Night shift work has been associated with a 20 to 30 percent increased risk of pregnancy loss (miscarriage), but the data regarding preterm birth are mixed, which may reflect the quantity of night shift work, gestational age of pregnancy, or other factors.

•A Danish nationwide register-based cohort study that used payroll data to verify shift measurement reported that women who had two or more night shifts the previous week had an increased risk of miscarriage after pregnancy week 8 (hazard ratio 1.32, 95% CI 1.07-1.62) and that the risk increased in a dose-dependent pattern with the cumulative number of night shifts [41]. The same study found that risk of preterm birth was not elevated among women working night shifts during either the first or second trimester and that, for night-shift workers, the risk did not relate to the number or duration of night shifts, consecutive night shifts, or quick returns defined as short intervals between shifts [42]. Working consecutive night shifts and quick returns after night shifts during the first 20 weeks of pregnancy were associated with an increased risk of hypertensive disorders of pregnancy, particularly among obese women who had up to a four- to fivefold increase [43].

•A meta-analysis of 62 observational studies reported working fixed night shifts was associated with increased risk of miscarriage (OR 1.23, 95% CI 1.03-1.47) and preterm birth (OR 1.21, 95% CI 1.03-1.42) [44]. However, the quality of the data was reported as being low to very low.

●Rotating and/or longer shifts – As compared with working a fixed-day shift, a meta-analysis of 62 studies found that working rotating shifts was associated with small increases in risk of preterm birth (OR 1.13, 95% CI 1.00-1.28), small-for-gestational age (OR 1.18, 95% CI 1.01-1.38), preeclampsia (OR 1.75, 95% CI 1.01-3.01), and gestational hypertension (OR 1.19, 95% 1.10-1.29) [44]. Working longer than 40-hour shifts was associated with miscarriage (OR 1.38, 95% CI 1.08-1.77), preterm birth (OR 1.21, 95% CI 1.11-1.33), low birth weight (OR 1.43, 95% CI 1.11-1.84), and small-for-gestational age (OR 1.16, 95% CI 1.00-1.36). Dose-response analysis showed that women working more than 55.5 hours (versus 40 hours) per week had a 10 percent increase in the odds of preterm birth.

●Shift work and child neurodevelopment – A national birth cohort study from Taiwan reported that persistent maternal shift work was associated with increased risks of delays in gross-motor neurodevelopmental milestones (adjusted OR 1.36, 95% CI 1.06-1.76 for walking steadily), fine-motor neurodevelopmental milestones (adjusted OR 1.39, 95% CI 1.07-1.80 for scribbling), and social neurodevelopmental milestones (adjusted OR 1.35, 95% CI 1.03-1.76 for coming when called) [45]. However, the clinical long-term significance of these changes is not known.

Lifting — In 2013, the National Institute for Occupational Safety and Health (NIOSH) published clinical guidelines for occupational lifting in uncomplicated pregnancies [10]. The recommended weight limits are based on gestational age, intermittent versus repetitive lifting, time (hours/day) spent lifting, and lifting height from floor and distance in front of body. Although not based on high-quality evidence, these guidelines are a reasonable reference for counseling pregnant women.

●Infrequent lifting

•Less than 20 weeks gestation – The maximum permissible weight is 36 pounds (16 kg).

•20 weeks gestation or greater – The maximum permissible weight is 26 pounds (12 kg).

●For repetitive lifting

•≥1 hour/day – The maximum weights in the first and second half of pregnancy are 18 pounds (8 kg) and 13 pounds (6 kg), respectively.

•<1 hour/day – The maximum weights are 30 pounds (14 kg) and 22 pounds (10 kg), respectively.

Supporting data regarding the increased risk of pregnancy loss with excessive lifting include:

●A study based on the Danish National Birth Cohort (1996 to 2002) of over 71,500 occupationally active women assessed the relationship between total weight lifted per day and miscarriage, which was not evaluated in the above guideline [13]. Compared to non-lifters, the hazard ratio (HR) for early miscarriage (≤12 weeks) increased in women who lifted a large amount of weight over the course of the day: 101 to 200 kg total weight lifted per day HR 1.38 (95% CI 1.10-1.74) and >1000 kg total weight lifted per day HR 2.02 (95% CI 1.23-3.33). Late miscarriage (13 to 21 weeks) was associated with total daily weight load but not with number of lifts per day. No association was found between occupational lifting and stillbirth. The study was adjusted for daily smoking, alcohol consumption, leisure-time physical exercise, leisure-time daily lifting, and predominant working posture (ie, primarily standing or walking, primarily sitting, or varying). Compared with non-lifters, the hazard ratio (HR) for early miscarriage (≤12 weeks) increased in women who lifted a large amount of weight over the course of the day: 101 to 200 kg total weight lifted per day HR 1.38 (95% CI 1.10-1.74) and >1000 kg total weight lifted per day HR 2.02 (95% CI 1.23-3.33). Late miscarriage (13 to 21 weeks) was associated with total daily weight load but not with number of lifts per day. No association was found between occupational lifting and stillbirth. The study was adjusted for daily smoking, alcohol consumption, leisure-time physical exercise, leisure-time daily lifting, and predominant working posture (ie, primarily standing or walking, primarily sitting, or varying).

●A meta-analysis of 80 observational studies including over 853,000 working pregnant individuals reported:

•Lifting objects 11 kg or greater was associated with increased odds of miscarriage (OR 1.31, 95% CI 1.08-1.58) and preeclampsia (OR 1.35, 95% CI 1.07-1.71) [46].

•Lifting objects for a combined weight of ≥100 kg per day was associated with increased odds of preterm delivery (OR 1.31, 95% CI 1.11-1.56) and low birth weight (OR 2.08, 95% CI 1.06-4.11).

●A separate meta-analysis of 51 studies reported that lifting 10 kg or more 10 times per day or more was associated with increased risks of spontaneous abortion (summary risk estimate 1.31, 95% CI 1.17-1.47) and preterm delivery (summary risk estimate 1.24, 95% CI 1.07-1.43) [37]. No association was identified with small for gestational age.

Stress — Whether working while pregnant increases or decreases a woman's overall stress likely depends on the woman's individual circumstances. As stress has been associated with poor reproductive outcomes, clinicians are encouraged to ask women about all sources of stress in their lives. In a national population-based control study in the United State, the most common source of emotional stress at work was dealing with unpleasant or angry people [36]. Women who identified as non-Hispanic Black or Hispanic were more likely to be in jobs in which they had to address angry or unpleasant people ≥75 percent of the time compared with non-Hispanic White women or women who identified as other.

While issues related to work, the occupational setting, and job requirements may increase stress, they also may have a positive influence both directly (eg, social support from coworkers) and indirectly (eg, income stability, maintenance of medical insurance, available nutrition, protection from interpersonal violence) [47]. In addition, significant stressors can develop in non-work-related aspects of the patient's life (eg, childcare, family illness). The influence of psychosocial factors on pregnancy outcomes may occur either directly via physiological pathways, or indirectly via behavioral pathways, or both. Psychosocial stress may also lead to unhealthy behaviors, including key behavioral risk factors for preterm birth such as poor diet/nutrition and smoking.

Maternal-placental-fetal neuroendocrine, immune/inflammatory and vascular processes all are responsive to stress, participate in the physiology of parturition, and may provide biological pathways that influence pregnancy outcome [48]. Stress is a common element activating a series of physiologic adaptive responses in the maternal and fetal compartments. Emerging data suggest that greater cardiovascular and neuroendocrine responses to acute stressors are predictive of poorer birth outcomes, but data are limited [47]. In addition, maternal stress may also play a role in the development (or mis-development) of neural networks, also known as the connectome [49]. One response involves activation of the hypothalamic-pituitary-adrenal (HPA) axis with increased secretion of corticotropin-releasing hormone (CRH), which can initiate preterm birth [50]. Another response involves chronic extended activation of the sympathetic nervous system with increased secretion of catecholamines, which may decrease uterine blood flow and, in turn, lead to increased secretion of placental CRH [9]. While a population-based cohort study reported that psychosocial work stress (high demands and low control) was not associated with an increased risk of congenital malformations, outcomes such as preterm birth, low birth weight, and hypertensive disorders of pregnancy were not studied [51]. However, such stress may have a complex interaction with physical demands [38]. (See "Spontaneous preterm birth: Pathogenesis", section on '#1 Stress-induced premature activation of the HPA axis'.)

SELECTED WORKPLACE EXPOSURES — The impact of selected workplace exposures on pregnancy outcomes are reviewed below. These issues, as well as exposure prevention, are presented in greater detail separately:

●(See "Overview of occupational and environmental risks to reproduction in females".)

●(See "Overview of occupational and environmental health".)

Obligations of employer — United States employers are mandated by law to provide information regarding work exposures that might affect reproductive outcomes (table 1). Exposure to these potential hazards should be minimized or avoided but do not necessarily warrant leaving the job. Some examples of potential hazards include [9]:

●Pharmaceuticals

●Battery acid

●Benzene

●Dyes used in manufacturing

●Formaldehyde

●Heavy metals

●Solvents

●Inorganic and organic particles

●Pesticides and herbicides

●Printing inks

●Radiation

●Products used in rubber, plastics, and textile manufacturing

●Wood preservatives

The Occupational Safety and Health Administration (OSHA) sets and enforces standards requiring employers to provide a workplace free from recognized hazards likely to cause serious physical harm. Every employer is mandated to have Hazard Communication Safety Data Sheets that contains information on chemicals that might cause hazards in the workplace. This format is more uniform than the older Material Safety Data Sheets. This sheet gives valuable information about pregnancy risk as well as the ingredients of a particular chemical, its appearance and odor, flammability, health hazards, reactivity data, precautions, spill and exposure procedures, preventive measures, and first aid measures.

Additional information on potential teratogens can be found at the following resources:

●The National Institute for Occupational Safety and Health (NIOSH) of the US Centers for Disease Control and Prevention.

●National Library of Medicine (NLM)

Bethesda, MD

800-638-8480

●Reprotox

Columbia Hospital for Women Medical Center

Washington, DC

202-293-5137

●Teratogen Information System (TERIS)

University of Washington

Seattle, WA

206-543-2465

●Pregnancy Exposure Registries

●MotherToBaby, Organization of Teratology Information Specialists (OTIS)

●Pediatric Environmental Health Specialty Units (PEHSU)

Impact of exposure

Industry-related

●Lead – Lead is the third most common occupational exposure in women and has been linked to a variety of adverse outcomes, including spontaneous abortion and impaired cognitive development. (See "Occupational and environmental risks to reproduction in females: Specific exposures and impact", section on 'Lead'.)

Under federal and state law, employers should have written lead standards and air monitoring results. Symptoms of lead toxicity (fatigue, muscle and joint pain, abdominal cramps, headaches, and irritability) appear when lead levels are between 60 and 120 mcg/dL in the blood. OSHA recommends a lead level less than 30 mcg/dL to prevent reproductive problems. However, neurologic, hematologic, and reproductive effects may occur at lower levels [52]. In pregnant women, blood lead elevations of 20 mcg/dL are of high concern because of the potential for adverse effects on the developing fetus, which is more susceptible to lead's toxic effects. Even lead levels less than 10 mcg/dL may be of concern in pregnancy in light of studies demonstrating intellectual impairment in children with blood lead concentrations below 10 mcg/dL.

Women working in known areas of lead exposure should always wear protective clothing, change work clothing and shoes before going home, use respiratory equipment to avoid inhalation, and wash hands before handling food and drinks [53]. The following figure illustrates the approach to management of women based on their serum lead level (figure 1). Additional information about the impact of lead exposure can be found separately:

•(See "Lead exposure, toxicity, and poisoning in adults", section on 'Pregnancy and breastfeeding'.)

•(See "Childhood lead poisoning: Exposure and prevention", section on 'Prenatal exposure'.)

●Mercury – The workplace is the major source of mercury exposure. While inhaling metallic mercury over time can affect all systems in the body, the brain and kidneys are the most likely to be affected at lower levels. In pregnancy, exposure to mercury can be associated with multiple adverse effects. Of note, occupational co-exposures to lead and mercury may interact, increasing the impact on infant development [54]. (See "Occupational and environmental risks to reproduction in females: Specific exposures and impact", section on 'Mercury' and "Mercury toxicity".)

Mercury can be found in elemental, inorganic, and organic forms. Elemental mercury is inhaled through vapors and fumes and is the least absorbed form of mercury. Persons working in light bulb manufacturing facilities, dental facilities, and gold-mining industries in undeveloped countries with high levels of mercury fumes have the greatest risks of elemental exposures. Women working with dental amalgam are at risk of exposure to elemental mercury. Inorganic mercury is found in fungicides, antiseptics and disinfectants and may be absorbed in toxic levels through the skin. Organic mercury is consumed by eating fish with high levels of methylmercury. (See "Fish consumption and marine omega-3 fatty acid supplementation in pregnancy".)

Mercury testing is indicated in patients at risk of high mercury exposure or who have symptoms of mercury toxicity [55,56]. Urine is used to test for exposure to elemental mercury (metallic mercury vapor, inorganic mercury). Blood or scalp hair is used to monitor exposure to methylmercury. (See "Mercury toxicity".)

●Inhaled inorganic and organic particles – Inhalation of both inorganic and organic particles at high levels during pregnancy appears to negatively impact fetal growth.

•Inorganic particle dust – In a nationwide cohort study in Sweden, women who had high exposure to inorganic particles and had less than 50 days of absence from work during pregnancy had an increased risk of [57]:

-Preterm birth (OR 1.18, 95% CI 1.07-1.30)

-Low birth weight (OR 1.32, 95% CI 1.18-1.48)

-Small-for-gestational-age infants (OR 1.20, 95% CI 1.04-1.39).

The increased risks were mainly due to iron particles; no increased risk was found for stone and concrete particles. High exposure to welding fumes was associated with an increased risk of low birth weight (OR 1.22, 1.02-1.45) and preterm birth (OR 1.24, 1.07-1.42).

•Organic particle dust – When assessing the impact of exposure to inhaled organic particles, the above Swedish national cohort study reported increased risks of preterm birth (OR 1.17, 95% CI 1.08-1.27), low birth weight (OR 1.19, 95% CI 1.07-1.32), and small-for-gestational age (OR 1.22, 95% CI 1.07-1.38) similar to the increased risks reported with exposure to inorganic particle dust [57].

•Products of oil and combustion – Subgroup analyses of the above Swedish national cohort study reported increased risks of small-for-gestational age with exposure to oil mist and combustion products, low birth weight for oil mist and cooking fumes, and preterm birth for paper and other organic dust [58].

●Pesticides – Every class of pesticide (organophosphates, carbamates, pyrethroids, herbicides, fungicides, fumigants, organochlorines) appears to have at least one agent capable of negatively affecting a reproductive or developmental endpoint in animals or humans. Epidemiologic studies have reported adverse reproductive or developmental outcomes with mixed pesticide exposure in occupational settings, particularly when personal protective equipment was not used [59,60]. A prospective cohort study found a fivefold increased risk of SGA for mothers exposed to pesticides (adjusted RR 5.45, 1.59-18.62) [61]. In a population-based case-control study assessing the association of organochloride pesticides and polychlorinated biphenyls (PCBs) with autism and intellectual disability (without autism), higher maternal serum levels of PCBs were associated with both conditions [62]. Strengths of the study included use of stored second-trimester serum to assess exposure and controlling for confounding that may have resulted from demographic factors. A review of 50 studies of prenatal and postnatal exposure to organophosphate pesticides found considerable evidence that they contribute to child neurodevelopmental disorders when evaluated at multiple points, including neonates, infants, toddlers, preschool children, and school-age children [63]. Counseling patients who are concerned about reproductive and developmental effects of pesticides involves helping them assess their degree of exposure, weighing risks and benefits of this exposure, and adopting practices to reduce or eliminate exposure and absorption. (See "Occupational and environmental risks to reproduction in females: Specific exposures and impact", section on 'Pesticides' and "Organophosphate and carbamate poisoning".)

●Solvents – Occupational exposure to solvents (eg, glycol ethers, carbon tetrachloride, trichloroethylene, methylene chloride) ranges from exposure to known toxic chemicals in the workplace to exposure to routine household solvents used for cleaning. Household solvents are usually not a major risk since exposure is episodic and air levels are low. However, women with industrial exposure appear to be at some risk [64-67], which depends on dose and duration of exposure. Exposure to organic solvents has been linked to congenital heart disease. In addition, one study has reported a possible association between maternal exposure to polycyclic aromatic hydrocarbons (PAHs) and an increased risk of craniosynostosis in the offspring [68]. Both maternal and paternal occupational exposures have been linked to sporadic retinoblastoma [69,70]. Impact on behavior also has been reported with increased externalizing behavior at age 2 in offspring of women with prenatal exposure to solvents (standardized score: 0.34 [0.11 to 0.57] for occasional exposure and 0.26 [0.05 to 0.48] for regular exposure) [71]. PAHs are used in a number of jobs, including the oil and gas industries, coal-fired and other power plants, and restaurants. (See "Overview of occupational and environmental risks to reproduction in females", section on 'Interference with fetal development'.)

We advise women working with occupational solvents to request information regarding the solvent from their employers, work in well-ventilated areas, and wear protective gear such as masks, gloves, and clothing while using these solvents [53].

Health care

●Pharmaceutical – Health care, veterinary, and some agricultural workers may be exposed to hazardous pharmaceutical agents. Exposure can occur through direct or indirect contact with these substances [72]. Although health care facilities recommend universal precautions, employees should ask for a Safety Data Sheet (SDS) when they work in areas exposed to hazardous materials. Hazardous materials should be prepared in well-ventilated areas, handlers should wear protective clothing (double gloves, gowns, eye protective gear), and all spills should be cleaned immediately and cleaning material discarded properly. Employers should provide training sessions to employees about hazardous materials in the workplace. It is required to have guidelines and procedures on handling and storage, use, preparation, cleaning spills, decontamination, first aid measures, handling accidental release, and firefighting measures.

Occupational exposures to chemotherapeutic agents have been linked to some adverse pregnancy outcomes. In a meta-analysis of seven studies, exposure to chemotherapy was associated with an increased risk of spontaneous abortion (odds ratio [OR] 1.46, 95% CI 1.11-1.92) but not with congenital malformations (OR 1.64, 95% CI 0.91-2.94) or stillbirths (OR 1.16, 95% CI 0.73-1.82) [73]. Evidence supporting an association between occupational exposure to inhalational anesthetics and reproductive toxicity is weak and biased from studies performed in the pre-scavenging era.

●Infection – Health care workers in particular are exposed daily, and often repetitively, to infectious agents (table 2). The likelihood of adverse sequelae if a pregnant woman becomes infected depends on several factors, including the type of infection and the trimester during which the exposure occurred (refer to individual topic reviews on each infection). Pregnant women working in health care facilities should always use universal precautions when coming in contact with children or adults who may have an infectious disease and should have appropriate immunizations before and during pregnancy (see "Immunizations during pregnancy").

Radiation — The United States Nuclear Regulatory Commission (NRC) lists limits for prenatal radiation exposure [74,75].

●Ionizing radiation – Pregnant individuals should not be exposed to more than 5 mSv during the nine months of pregnancy and no more than 0.5 mSv during any gestational month. Similar to non-pregnant persons, pregnant individuals working in an environment with radiation exposure should wear a dosimeter badge, which is processed every two to four weeks. They should also be encouraged to wear proper shielding (eg, lead apron) if exposure is expected, minimize the time of exposure, and maximize their distance from the source of radiation. The risks of radiation exposure in pregnancy are discussed in detail separately. (See "Diagnostic imaging in pregnant and lactating patients".)

●Non-ionizing radiation – Non-ionizing radiation (eg, electromagnetic fields emitted from computers, microwave communication systems and ovens, power lines, cellular phones, household appliances, heating pads and warming blankets, airport screening devices for metal objects) appear to have minimal reproductive risk. Video display terminals (VDTs) emit very low frequency and extremely low frequency electromagnetic fields. Literature reviews have generally concluded that there is no evidence of a significant association between a woman's use of a VDT and fetal loss or other adverse reproductive outcomes [76,77]. However, ergonometric issues related to use of computers in the workplace (eg, carpal tunnel syndrome, low back pain) may be more problematic for pregnant women. (See "Radiation risk to healthcare workers from diagnostic and interventional imaging procedures".)

●Air travel – Radiation exposure from the environment during air travel is reviewed below. (See 'Environmental' below.)

Environmental

●Heat – The human fetus' temperature is approximately 1°C higher than the maternal temperature. Animal studies suggest that perinatal risks (eg, central nervous system, vascular disruption, neural defects [78]) increase with maternal heat exposure. Similar findings were found in human studies related to febrile illnesses, sauna use, and hot tub use [79-81].

The National Institute of Occupational Safety and Health (NIOSH) guidelines address protection of workers in hot environments [82]. Employers of facilities with risk for high temperature should institute measures to minimize environment and metabolic heat exposure (eg, good ventilation to draw steam and heat from work areas, cooling fans, heat shields, labor saving devices, rest periods in cooler areas, hydration) and provide training to employees on how to recognize heat-related illnesses. In areas where heat is unavoidable, employees should take precautions to avoid heat stress and heat-related complications. Pregnant women should be encouraged to increase fluid intake, request periodic breaks from the heated area, and dress in light clothing to avoid overheating. A resource sheet on Reproductive health and the workplace: Heat is available from the NIOSH.

●Cold – All workers exposed to extreme cold are at risk of cold stress, which may be exacerbated by vasodilation from pregnancy. There are limited data on the effect of environmental cold stress on pregnancy outcome, including a few studies on therapeutic hypothermia. (See "Sudden cardiac arrest and death in pregnancy", section on 'Postarrest care'.)

For women who work outdoors in cold climates, dressing appropriately and taking care to avoid falling on icy surfaces is practical advice. A resource sheet on Cold stress is available from the NIOSH.

●Noise – Most countries have regulations about occupational noise exposure, but these standards typically do not specifically address pregnant women and fetal safety. In the United States, the NIOSH recommends that workers should not be exposed to noise at a level that amounts to more than 85 decibels (dB) for eight hours [83]. The NIOSH has published a fact sheet on Controls for noise exposure. There is no method for shielding the fetus from environmental noise.

•Impact on pregnancy outcome – A national cohort study of over 857,000 births in Sweden reported that, for full-time workers, exposure to high (>85 dBA) levels of occupational noise throughout the pregnancy increased risk of SGA (OR 1.44, 95% CI 1.01-2.03) and LBW (OR 1.36, 95% CI 1.03 1.80) compared with exposure of <75 dBA [84]. No clear association was seen for preterm birth.

•Hearing dysfunction – Environmental noise, if sufficiently loud, may damage fetal hearing, although data in humans are limited [85-89]. In one well-designed prospective national cohort study, those working full-time with <20 days of leave during pregnancy and ≥85 dB exposure had a hazard ratio of 1.82 (95% CI 1.08-3.08) for hearing dysfunction compared to those with <75 dB exposure. By the 20^th week of gestation, the structures of the fetal auditory system are well-developed, enabling the fetus to detect sounds after the late second trimester of pregnancy [90]. Low-frequency sounds penetrate the maternal tissues and amniotic fluid more effectively than higher frequency sounds: external noise is minimally reduced for frequencies below 0.5 kHz but reduced by 40 to 50 dB for frequencies above 0.5 kHz [91].

●Airborne – Women who work outside in urban areas have more exposure to air pollution than other individuals. Numerous studies have examined the links between various airborne pollutants and adverse outcomes, such as low birth weight, preterm birth, and small for gestational age birth, and have come to different conclusions because of difficulties in measuring exposures, timing of measurements, and degree of adjustment for confounding. (See "Occupational and environmental risks to reproduction in females: Specific exposures and impact", section on 'Air pollution'.)

Environmental tobacco smoke may also have an adverse effect on the fetus, but data are limited. The effects of passive and active smoking on pregnancy are discussed in detail separately. (See "Secondhand smoke exposure: Effects in adults" and "Cigarette and tobacco products in pregnancy: Impact on pregnancy and the neonate", section on 'Effects of secondhand smoke'.)

Similarly, marijuana exposure, including in new occupations related to production and sale in many states, may convey risk. (See "Substance use during pregnancy: Overview of selected drugs", section on 'Cannabis (marijuana)'.)

●Air travel – While air travel is common and generally safe during pregnancy, aircrew or frequent flyers may exceed limits. The Federal Aviation Administration and the International Commission on Radiological Protection consider crew to be occupationally exposed to ionizing radiation and recommend that they be informed about radiation exposure and health risks [92]. Issues related to air travel are discussed separately. (See "Prenatal care: Patient education, health promotion, and safety of commonly used drugs", section on 'Airline travel'.)

●Cosmetics – Workers in hair and nail salons are potentially exposed to hundreds of chemicals. There is no strong evidence of teratogenic effects, but it is prudent for these workers to wear gloves when possible and attempt to work in well-ventilated areas since data are limited [93-99]. Information on Nail technicians' health and workplace exposure control is available from the NIOSH.

LEGAL ISSUES

Summary — Women in the workplace and their clinicians should understand the rights of pregnant women in the workplace, familiarize themselves with local and national laws about maternity leave, review the duration of and benefits granted during maternity leave, and understand expectations about their return to the workplace. Women who have concerns about treatment during pregnancy, including potential job discrimination, denial of accommodations, need for extended medical leave, or other complex employment questions arise, are advised to consult legal services [100].

Legal and regulatory issues vary among countries and between states in the United States. A synopsis of laws that serve as the basis of the United States federal legal framework, which applies in all states, is described below. These laws include the Pregnancy Discrimination Act (PDA) of 1978, the Americans with Disabilities Act (ADA) of 1990, and the Family Medical Act (FMLA) of 1993. These and related court rulings clarify legal expectations related to potential discrimination of pregnant women, their protection related to any occupation related disability, and employer provided benefits to which they are entitled.

Pregnancy Discrimination Act — The Pregnancy Discrimination Act (PDA) of 1978 amended Title VII of the Civil Rights Act of 1964 to prohibit sex discrimination on the basis of pregnancy, childbirth, or related medical conditions. This act requires employers with 15 or more employees to offer medical disability benefits for pregnancy-related disabilities just like all other temporary disabilities under any health, disability, insurance or sick leave plan [101]. Pregnant workers must be provided the same insurance benefits, accommodations, sick leave, seniority credits, and reinstatement privileges awarded workers disabled by other causes. In March 2015, the Supreme Court of the United States held that a pregnant employee can make a prima facie case of discrimination by demonstrating that "she belongs to the protected class, that she sought accommodation, that the employer did not accommodate her." Such circumstances may merit a summary judgement standard "by providing evidence that the employer accommodates a large percentage of nonpregnant workers while failing to accommodate a large percentage of pregnant workers."

If an employer requires employees to obtain a clinician's note when taking sick leaves and collecting benefits, the same rule can be applied to pregnant employees.

In the United States, federal law prohibits discrimination due to pregnancy, childbirth, or related medical conditions under the PDA and ADA [102,103]. The ADA Amendments Act (ADAAA) in 2008 directed the Equal Employment Opportunity Commission to modify the degree of limitation defined as a disability replacing "severely or significantly" with "substantially limits," a more lenient standard. The ADA and ADAAA also apply to employers with 15 or more employees, including state and local governments. Provisions include:

●Pregnant employees must be allowed to work so long as they can perform their jobs. Women who are pregnant or affected by related conditions must be treated in the same manner as other applicants or employees with similar abilities or limitations.

●Accommodations must be provided for pregnant women, regardless of the severity of their pregnancy-related work limitations, if similar accommodations are provided to other employees with similar abilities or inabilities to work. For example, if an employer provides alternative work for nonpregnant employees who are unable to perform their usual lifting duties or heavy physical labor because of back issues, the employer must make similar arrangements for a pregnant employee.

●Employers cannot require a pregnant employee to take leave due to the pregnancy so long as she can perform their job. If an employee takes leave for a pregnancy-related condition and recovers, an employer cannot require them to remain on leave.

●Employers may not refuse to employ a person because of their pregnancy, a pregnancy-related condition, or the prejudices of coworkers or customers.

In 1991, the Supreme Court ruled that a rigid policy that banned women of reproductive age from certain jobs discriminated against women on the basis of their sex. Although several toxic substances found in the workplace also could harm men of reproductive age, men were not banned from jobs on that basis. Therefore, it is illegal for an employer to ban a woman from certain jobs because she might become pregnant while working there.

Despite these legal protections, literature suggests that women may not be able to take advantage of full PDA policies. Women report a combination of discrimination, including racial, sex, ethnicity, and economic biases. These biases impact decisions on work continuation and work treatment [104].

Family Medical Leave Act — In the United States, the FMLA enacted in 1993 "entitles eligible employees of covered employers to take unpaid, job-protected leave for specified family and medical reasons with continuation of group health insurance coverage under the same terms and conditions as if the employee had not taken leave" [105]. The benefit applies to workers in same-sex relationships as well as heterosexual couples.

To be eligible for FMLA coverage, an employee must have worked more than half-time (1250 hours) for at least one year at a company where more than 50 employees work at that location or within 75 miles [105]. Based on this requirement, more than 40 percent of workers are not eligible [106]. However, some state laws expand coverage to employees of employers with fewer workers, including Vermont (10 employees), Maine and Maryland (20), the District of Columbia (20), Minnesota (21), Oregon (25), and Rhode Island (public employers, 30; private employers, 50). Washington State requires all employers to provide parental leave.

Eligible employees are entitled to the equivalent of 12 work weeks of (unpaid) leave in a 12-month period [107]. This may be a continuous leave of absence (one block of time, generally 3+ days); multiple, consecutive continuous leaves between intervals of work; intermittent leave of absence (any regular interval of absences that don't follow a schedule such as an hour appointment once a month or several days a year); or reduced leave of absence (scheduled, such as when employees can only work four hours a day maximum, miss every Tuesday/Wednesday, or similar). In cases where both spouses work for the same employer, the combined FMLA leave for an uncomplicated birth is 12 weeks, although individual 12-week leaves may apply in case of a complicating serious condition (maternal or newborn). Leaves may be taken for the following indications [105]:

●The birth and care of a child within one year of birth

●The placement and care of an adopted or foster child within one year of placement

●To care for the employee's spouse, child, or parent who has a serious health condition

●A serious health condition that makes the employee unable to perform the essential functions of their job

●Any qualifying need stemming from the fact that the employee's spouse, son, daughter, or parent is a covered military member on "covered active duty"

●Twenty-six workweeks of leave during a single 12-month period to care for a covered service member with a serious injury or illness if the eligible employee is the service member's spouse, son, daughter, parent, or next of kin (military caregiver leave)

Federal law also states that when the need for leave is foreseeable based on an expected birth or planned treatment, an employee must give at least 30 days' notice of such leave to the employer. If such notice is not possible, an employee is required to provide notice "as soon as practicable," generally interpreted as verbal notice within one to two business days.

Maternity leave — The FMLA, similar to the PDA, requires a continuation of benefits during pregnancy-related leave similar to that provided to other disabled employees, including maintenance of the employee's group health benefits [105]. In the United States, women with greater resources, as reflected in access to paid maternity leave, were more likely to have insurance coverage continued postpartum, less likely to lose private or public health insurance, and much less likely to become uninsured after giving birth [108]. (See 'Family Medical Leave Act' above.)

In addition, an employer cannot prohibit an employee from taking less time than the maximum. For example, the employee may choose to work until their delivery and return to work soon after or she may take leave for an antepartum problem and return to work before delivery if the problem resolves.

Given these issues, women of reproductive age searching for employment often evaluate employer policies on maternity leave as well as policies on issues related to childcare, such as flexible schedules, part-time work, working from home, leaving early for child-related needs, sick children/snow days, dependent care spending accounts, childcare assistance, resource and referral programs, etc.

Federal oversight — The Equal Employment Opportunity Commission (EEOC) provides federal oversight of certain employer activities involving discrimination, including those related to pregnancy [109]. Its Policy guidance related to pregnancy discrimination, issued in 2014, provides an overview. The United States Department of Labor Wage and Hour Division enforces issues pertaining to the FMLA. The Fact Sheet for Small Businesses: Pregnancy Discrimination may be of help in understanding federal requirements as they pertain to small businesses.

In the United States, pregnancy discrimination remains prevalent and represents a large portion of claims brought against employers by women. During fiscal year 2019, the EEOC received 2753 complaints about pregnancy discrimination [110]. Almost 31,000 charges of pregnancy discrimination were filed with the EEOC and state-level fair employment practice agencies during fiscal years 2011 to 2015, of which 31 percent were filed by women alleging they were discharged for becoming pregnant [111,112]. Women also reported being denied the minor job modifications they needed to continue working while pregnant, (eg, more frequent bathroom breaks or availability of a water bottle).

The EEOC reports that pregnancy-related violations have involve a variety of complaints, including [113]:

●Refusing to hire, failing to promote, demoting, or firing pregnant workers after learning they are pregnant.

●Discharging workers who take medical leave for pregnancy-related conditions (such as a miscarriage).

●Limiting employment opportunities for pregnant women, such as by refusing to hire them, placing them on involuntary leave, refusing to let them continue working beyond a certain point in the pregnancy, reducing work hours, or limiting work assignments due to employer safety concerns.

●Requiring medical clearances not required of non-pregnant workers.

●Failing to accommodate pregnancy-related work restrictions where similar accommodations are or would be provided to non-pregnant workers.

●Refusing to allow lactating mothers to return to work.

●Retaliating against employees, or those close to pregnant employees, who complained about pregnancy discrimination.

Paid leave in the United States — While the FMLA provides for unpaid leave, eight states have passed legislation requiring paid and medical leave of varying lengths; these include California, Connecticut (benefits start in 2022), Massachusetts (benefits start in 2021), New Jersey, New York, Oregon (benefits start in 2023), Rhode Island, and Washington state, as well as the District of Columbia and Puerto Rico. Those in Rhode Island, New York, and Washington provide job protections that go beyond those provided by the FMLA. All allow leave to care for a newborn or adopted child, a seriously ill family member, or a serious health condition. Many other states have proposed legislation to establish paid family leave programs or less expansive efforts, such as tax credits for employers to bring paid leave to more workers. Additional states currently provide paid leave only to state employees [114].

The impact of expanded paid leave programs include:

●Reduced postneonatal mortality and improved general health outcomes – California implemented its expanded leave policy in 2004. Subsequent studies have reported:

•Reduced postneonatal mortality – In the four years following policy implementation, postneonatal mortality rates decreased 12 percent (adjusted odds ratio 0.88, 95% CI 0.80-0.97) with no differences in the effect by race/ethnicity or insurance status except for an increase in low birth weight births among privately insured women [115].

•Improved health outcomes – A analysis found robust improvements in self-rated health and psychological distress, as well as decreased likelihood of being overweight and reduced alcohol consumption (greater for fathers) [116].

•Increased use of leave time - The number of women in California on leave at any time doubled (5.4 to 11.8 percent) [117].

●Increased use of postpartum visits – In 2014, Rhode Island began offering an additional four weeks of wage replacement in addition to coverage from temporary disability policies (expanded benefit of up to 10 weeks for vaginal delivery and 12 weeks for cesarean delivery) [118]. Compared with other northeastern states, increased availability of paid leave in Rhode Island was associated with a two-percentage-point increase in receiving postpartum care across all postpartum individuals (2.18 percentage point increase, 95% CI 0.5-3.7) [119]. This effect was greatest among persons of underrepresented racial groups (3.38 percentage point increase, 95% CI 1.12-5.63).

●Improved mental and physical health outcomes – A review reported that paid maternity leave improved multiple aspects of mental and physical health of mothers and children, including [120]:

•Decreased rates of postpartum maternal depression, intimate partner violence, infant mortality, and mother and infant rehospitalizations.

•Improved infant attachment and child development.

•Increased pediatric visit attendance, timely administration of infant immunizations, and initiation and duration of breastfeeding.

International perspective — Except for the United States, all 42 countries in the Organization for Economic Cooperation and Development (OECD) provide a national paid maternal leave policy [121]. Using full-pay equivalent time, leaves range from 12 weeks (United Kingdom and Mexico) to 36 weeks (Japan) to 85 weeks (Estonia) [122]. A comparison of family-related benefits among European countries and the United States is presented in the table (table 3).

Studies of these expanded leave programs have reported:

●Lack of impact of expanded prenatal leave – Austria increased mandatory prenatal leave from six to eight weeks (starting at 33 weeks of pregnancy) [123]. However, this extension had no effect on children's health at birth, long-term health, or subsequent maternal health and fertility. The authors concluded that employment during the 33^rd and 34^th week of gestation is not harmful for expectant mothers.

●Increased likelihood of postpartum employment – In Spain, women who took paid maternity leave were more likely to be employed one year after childbirth (OR 2.7, 1.6-4.5), including after adjusting for staying at work until late in pregnancy (OR 1.8, 1.0-3.1) [124].

ROLE OF HEALTH CARE PROVIDER

Workplace accommodations and leave — Clinicians caring for working pregnant women are often asked for advice and documentation for workplace accommodations or medical leave [125]. The basis for such requests may stem from the nature of the woman's work (eg, extreme physical activity, toxin exposure), from the pregnancy and pregnancy-related complications (eg, twins, placenta previa), or from nonpregnancy medical morbidities (eg, cardiovascular disease). Advising women that they may be eligible for leave can be helpful.

●Workplace accommodations – Workplace accommodations are "reasonable adjustments to your duties or work setting to allow you to continue working safely while pregnant or recovering from pregnancy" [126]. Examples of reasonable adjustments include temporary transfer to a less hazardous or strenuous job, provision of modified equipment or devices (eg, providing a stool for cash register clerk), more frequent or longer breaks, and working from home (table 4).

●Medical leave – Medical leave is time away from work for the woman who cannot safely perform the essential components of her job because of pregnancy, childbirth, or related medical conditions [126]. Medical leave typically applies to complications of pregnancy or childbirth. Being pregnant is itself not a disability. Impairments that are automatically considered disabilities are listed by the United States Social Security Administration.

Issues for consideration — In assessing the need for accommodations or medical leave, the clinician must consider the following issues:

●Nature and perception of risk – While "risk" is defined as the likelihood of occurrence of an adverse event, risk perception includes the person's expectations about the probability of an event, and the myriad meanings and weights the individual assigns to being at risk [127]. These in turn influence the actions the person takes related to the risk, including, for a pregnant person, those related to her work. The prenatal care clinician's understanding of a pregnant person's perceptions related to occupational risks is critical to assisting her in choosing an appropriate response to them. The clinician must assess:

•The type of risk and the likelihood that it will affect the person or their pregnancy.

•The person's understanding of the concept of risk and perception of the degree of risk involved.

•The timing of the risk (eg, exposures may be of maximum risk during particular developmental intervals, while activity-related risks may increase in magnitude as pregnancy progresses).

•Manager and coworker awareness and response to the person's pregnancy. One study found that in unsupportive organizations, use by women of strategies of maintaining the person's prepregnancy image decreases work-family stress and conflict, while strategies to avoid negative outcomes by hiding the pregnancy or dodging the issue may increase work-family conflict [128].

●Laws and regulations – The clinician needs to understand the federal, state, and local laws related to pregnancy accommodations and disability leave.

●Employer- and job-related factors.

•Whether reduction of risk is possible through workplace accommodations (including progressive over time) or requires a leave, and the required duration of such modification necessary.

•Whether the necessary alteration in work activities involves essential work functions of the person's job.

•Whether the employer has a light duty program and the employer's history of providing accommodations to other employees, pregnant people, or those with disabilities.

●Psychosocial

•The availability of resources to the person to assist in obtaining a satisfactory response from her employer (eg, employer human resources, union, legal, or social services, etc).

•Whether the person is currently willing to disclose her pregnancy to her employer.

•The person's financial resources and employment alternatives both with her current employer and elsewhere.

•Potential risks related to taking a leave (isolation, loss of insurance, family violence) and options to minimize their effects.

Certification and sharing health information — In contrast to Family Medical Leave Act (FMLA) certification, to be protected by the Americans with Disabilities Act (ADA), a patient must have a specific impairment that "substantially limits one or more major life activities" [102]. The ADA does not list all qualifying impairments.

The FMLA regulations clarify that communication with an employer must comply with the Health Insurance Portability and Accountability Act (HIPAA) privacy regulations. The FMLA certification may be written to be sufficiently vague so that HIPAA laws are not violated, for instance providing only an estimation of treatment and/or absences which cannot be reliably linked to specific diagnoses. However, obtaining the patient's consent to disclosure of HIPAA protected information may facilitate planning and discussion of schedule and accommodations.

When a pregnant person initially seeks leave for an FMLA-qualifying reason, she must provide sufficient information to make the employer aware of the need for FMLA leave and the anticipated timing and duration of the leave. However, she does not need to mention FMLA; FMLA designation is at the discretion of the employer. Generally an employer may retroactively reclassify other leave time (eg, sick time, paid vacation) to be part of an FMLA leave only if they do so within two business days of becoming aware that the leave qualified as FMLA leave. This may alter the maximum duration of total allowable leave. Depending on the situation, sufficient information may include that the employee is pregnant or has been hospitalized overnight or that she is unable to perform the functions of the job.

While an employee is not required to give the employer her medical records or sign a release of information, the employer does have the right to request medical certification containing sufficient medical facts to establish that a serious health condition exists. Such a request for medical certification should occur within five business days of when the employee gives her notice (or takes an unplanned leave); however, certification may be requested at a later date if the employer has reason to question the appropriateness or duration of the leave. (See 'Writing a medical certification letter' below.)

Employers may contact an employee's health care provider to authenticate or clarify the medical certification, but only with the employee's consent [129]. This contact should occur through an employer's human resource professional, leave administrator, or other management official. However, FMLA regulations specify that in no case may the employee's direct supervisor contact the employee's health care provider. Provision of individually identifiable health information requires the written authorization of the employee, allowing the health care provider to disclose such information to the employer. Employers may not ask for information beyond that contained on the medical certification form.

Writing a medical certification letter — Most healthy pregnant women do not meet the definition of disability and thus do not qualify for an alteration in their work status before the onset of labor. Further, if a clinician writes that a pregnant worker is unable to perform the essential duties of her job, and accommodations cannot be made that do not create an "undue hardship" for the employer, she could be terminated if she is not eligible for leave or if she uses all her available leave [125].

Common requests for work restrictions and suggested note-writing instructions are presented in the table (table 5 and table 6), and a sample work letter is presented in the form (form 1). Employers may provide forms for FMLA requests although they may not require that they be used. Federal forms are available (https://www.dol.gov/agencies/whd/fmla/forms), but employers are required to accept any format that conveys complete and sufficient information.

Prior to composing a medical certification letter requesting an accommodation or leave, the clinician and person need to discuss [100,125]:

●Is a work restriction really necessary?

●Does the person's pregnancy-related condition prevent her from safely performing an "essential function" (these include primary duties) of her job?

●Is an accommodation in work duties sufficient to mitigate the risk?

●Does the employer have a light-duty program or policy for employees with temporary incapacity?

●Is the need for accommodation likely to be time-limited, or will it extend to the end of the pregnancy? When will the accommodation need to be initiated?

●Can the accommodation be progressive in scope, including possibly leading up to a leave? If so, what guidance can be given regarding the progressive steps (eg, duration of standing, limits on weight lifted, total work hours) and the timing of the start of a terminal leave?

●Is the total time of pregnancy-related leave (including postpartum) likely to exceed the 12 weeks (or longer depending on state or city statutes) of job protection provided by Family Medical Leave Act?

Ascertaining that the person recognizes the risk and is basing her perceptions related to it on an adequate understanding of the nature and magnitude of the risk, along with developing an understanding of the values and priorities of the person, provides the basis for further discussion. (See 'Issues for consideration' above.)

To be of greatest benefit, a medical certification should include [125]:

●The specific pregnancy-related impairment for which the accommodations or leave is requested

●When the condition started and how long it may last, or the date of re-evaluation if duration is uncertain

●Whether the person will be capable of performing her position's essential functions

●The specific limitations required

●The timing of the initiation and any stepped increase of accommodations

●Suggested accommodations

RESOURCES FOR PATIENTS AND CLINICIANS

●Pregnant@work – A free website from the Center for WorkLife Law, University of California, Hastings College of the Law that provides general information, tools, and educational materials about accommodating pregnant women at work

●Family Medical Leave Act

●Americans with Disabilities Act

●Pregnancy Discrimination Act

●American College of Obstetricians and Gynecologists provides guidance for ACOG members

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: General prenatal care".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Activity during pregnancy (The Basics)")

SUMMARY AND RECOMMENDATIONS

●As the number of women in the workforce has risen, so has the number of women working while pregnant. In addition, women are working later into their pregnancies than ever before. (See 'Prevalence' above.)

●While many individuals work while pregnant without any interference from pregnancy-related changes, problems of nausea and vomiting, pain, and fatigue can negatively impact a person’s work performance. Despite data limitations, working while pregnant generally does not appear to negatively impact maternal or fetal health. However, the physical demands of the individual’s job should be considered on a case-by-case basis, especially for those at higher risk of preterm delivery or who have medical or obstetric disorders that are unstable or associated with impaired placental perfusion (eg, preeclampsia, fetal growth restriction). (See 'Impact' above.)

●To date, the available evidence does not justify imposing mandatory restrictions to working hours, shift work, lifting, standing, and physical work during pregnancy. Challenges to writing such guidelines include the lack of data demonstrating a clear cut-off at which work is detrimental to the health of most pregnant persons and fetuses as well as the reality that some people must continue working while pregnant for economic reasons, regardless of medical advice. Any guidelines must also balance the data suggesting that some level of physical activity while pregnant is healthy. (See 'Work characteristics' above.)

●In the United States, the Occupational Safety and Health Administration (OSHA) sets and enforces standards requiring employers to provide a workplace free from recognized hazards likely to cause serious physical harm. Every employer is mandated to have a Hazard Communication Safety Data Sheets that contain information on the chemical properties and health effects of the substances used in the workplace. Exposure to these potential hazards should be minimized or avoided, but do not necessarily warrant leaving the job. (See 'Obligations of employer' above.)

●Clinicians caring for working pregnant persons are often asked for advice and documentation for workplace accommodations or medical leave. (See 'Workplace accommodations and leave' above.)

•Workplace accommodations are "reasonable adjustments to your duties or work setting to allow you to continue working safely while pregnant or recovering from pregnancy." (See 'Workplace accommodations and leave' above.)

•Medical leave is time away from work for the individual who cannot safely perform the essential components of the job because of pregnancy, childbirth, or related medical conditions. Medical leave typically applies to complications of pregnancy or childbirth. Being pregnant is itself not a disability. Impairments that are automatically considered disabilities are listed by the United States Social Security Administration. (See 'Workplace accommodations and leave' above.)

●Pregnant persons should understand their rights in the workplace, familiarize themselves with local and national laws about maternity leave, review the duration of and benefits granted during maternity leave, and understand expectations about their return to the workplace. To be protected by the Americans with Disabilities Act (ADA), a patient must have a specific impairment that "substantially limits one or more major life activities." Most healthy pregnant women do not meet the definition of disability and thus do not qualify for an alteration in their work status before the onset of labor. (See 'Legal issues' above.)