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INTRODUCTION — Before insulin became available in 1922, individuals with diabetes mellitus were at very high risk of complications of pregnancy. Today, most individuals with diabetes can have a safe pregnancy and birth, similar to that of individuals without diabetes. This improvement is largely due to good blood glucose (sugar) management, which requires adherence to diet, frequent daily blood glucose monitoring, and frequent insulin adjustment.
This topic review discusses care of individuals with type 1 or 2 diabetes during pregnancy, as well as fetal and newborn issues. It does not address gestational diabetes, which is diabetes that is first diagnosed during pregnancy. (See "Patient education: Gestational diabetes (Beyond the Basics)".)
IMPORTANCE OF BLOOD GLUCOSE CONTROL — Glucose in the mother's blood crosses the placenta to provide energy for the baby; thus, high blood glucose levels in the mother lead to high blood glucose levels in the developing baby as well.
High blood glucose levels can cause several problems:
●Early in pregnancy, high glucose levels increase the risk of pregnancy loss and congenital anomalies. These risks are highest when glycated hemoglobin (hemoglobin A1C or A1C) is >8 percent or the average blood glucose is >180 mg/dL (10 mmol/L). As hemoglobin A1C levels increase above 8 percent, the risk of congenital anomalies increases in a stepwise fashion.
●In the last half of pregnancy and near delivery, high blood glucose levels can cause the baby's size and weight to be larger than average and increase the risk of complications during and after birth (see 'Newborn issues' below). In particular, individuals with large babies are more likely to have difficulty with a vaginal birth and have a higher chance of needing a cesarean birth.
●In the last half of pregnancy, individuals with diabetes are more prone to developing pregnancy-induced hypertension (preeclampsia and gestational hypertension) and an excessive amount of amniotic fluid (polyhydramnios). High blood glucose levels in late pregnancy can also increase the risk of stillbirth.
These complications occur less frequently when blood glucose levels are well controlled, so it is important to have blood glucose as well controlled as possible before conception and throughout pregnancy.
General measures to control blood glucose
●Individuals with type 2 diabetes who have been treated with diet or oral medications generally require insulin for blood glucose control during pregnancy. Although oral diabetes medications (eg, glyburide, metformin) can be used to manage type 2 diabetes during pregnancy in a small number of individuals, the majority need to be switched to insulin therapy during pregnancy. Individuals who are taking oral medications when they become pregnant should speak with their health care provider about whether to continue oral medication or switch to insulin therapy.
●Most individuals with type 1 diabetes will require two to five insulin injections per day depending on the route of administration (syringes or pens). Individuals who use an insulin pump may continue to do so during pregnancy. (See "Patient education: Type 1 diabetes: Insulin treatment (Beyond the Basics)".)
●Most individuals with type 1 or type 2 diabetes need more insulin during pregnancy, especially during the last one-third of pregnancy (approximately 26 to 40 weeks of pregnancy) because the body becomes resistant to insulin as the pregnancy progresses.
●The abdomen is the preferred site for insulin injections during pregnancy because absorption of the medication is better. Insulin can be injected any place in the abdomen where an inch of belly fat can be pinched, even in late pregnancy. The back of the arm may also be used.
●Frequent contact with health care providers is important for managing blood glucose levels and monitoring maternal health and the baby's health. The health care provider may want to review blood glucose levels and insulin doses one or more times per week; this can usually be done via telephone, email, fax, or through the electronic medical record.
●A nutritionist can help to plan a diet that provides the optimal number of calories; proportion of calories from carbohydrates, protein, and fat; and distribution of calories across snacks/meals throughout the day. The optimal number of calories depends upon the individual's prepregnancy weight and activity level.
●Exercise is an excellent way to control weight and blood glucose levels. Most individuals who exercised before pregnancy can continue to do so during pregnancy at the same or a slightly reduced pace. Moderate-intensity exercise, such as brisk walking, is recommended. Individuals who did not exercise previously may begin to exercise during pregnancy after consulting with their health care provider. Exercise intensity, type, and duration may need to be modified as the pregnancy progresses or if complications develop. (See "Exercise during pregnancy and the postpartum period".)
Target blood glucose levels — Frequent blood glucose monitoring is recommended during pregnancy, including testing before and after each meal. (See "Patient education: Glucose monitoring in diabetes (Beyond the Basics)".)
The American College of Obstetricians and Gynecologists (ACOG) and American Diabetes Association (ADA) recommend the following goals when self-monitoring blood glucose levels during pregnancy:
●Fasting glucose concentrations ≤95 mg/dL (5.3 mmol/L)
●Preprandial glucose concentrations ≤100 mg/dL (5.6 mmol/L)
●One-hour postprandial glucose concentrations ≤140 mg/dL (7.8 mmol/L)
●Two-hour postprandial glucose concentrations ≤120 mg/dL (6.7 mmol/L)
●Mean capillary glucose 100 mg/dL (5.6 mmol/L)
●During the night, glucose levels ≥60 mg/dL (3.3 mmol/L)
Continuous glucose monitoring (CGM) can also be used as an adjunct way to monitor blood glucose levels, primarily in individuals with type 1 diabetes. The devices are most often used with insulin pumps but are also used by some individuals taking multiple insulin injections. The goal is to help the individual achieve a higher percentage of time in range (TIR) during the day while both decreasing the time above range (TAR) and time below range (TBR).
Guidelines for blood glucose monitoring for type 1 diabetes using CGM include the following:
●Target range for blood glucose: 63 mg/dL to 140 mg/dL (3.5 mmol/L to 7.8 mmol/L).
●TIR >70 percent (ie, >16 hours, 48 minutes)
●TAR <25 percent (ie, <6 hours)
●TBR <4 percent (ie, <1 hour) with <1 percent of time <54 mg/dL (<3.0 mmol/L; ie, <14 minutes)
CGM targets for patients with type 2 diabetes in pregnancy have not been set due to lack of evidence from clinical studies.
Hemoglobin A1C is a blood test that represents the average blood glucose level over the previous two to three months. This test may be done once per trimester during pregnancy or more frequently as recommended by the health care provider. Ideally, the goal is for the A1C to be at or near normal (6 percent or an average blood glucose of 120 mg/dL [6.7 mmol/L]) (table 1). However, attempting to be at or below 6 percent can cause frequent episodes of low blood glucose, which should be avoided. The target may be relaxed to <7 percent (53 mmol/mol) if necessary to avoid low blood glucose (see "Patient education: Hypoglycemia (low blood glucose) in people with diabetes (Beyond the Basics)"). Elevated levels of A1C at the time of conception and in the first trimester have been linked to an increased rate of birth defects, highlighting the need for preconception glucose control.
CARE DURING PREGNANCY — Ideally, an individual with diabetes who is planning pregnancy should consult their health care provider well before they become pregnant. This provides an opportunity to make sure blood glucose levels are in optimal control, adjust medications if needed, evaluate and treat any medical complications related to diabetes (such as diabetes-related eye disease, thyroid disease, hypertension), and begin folic acid supplementation (at least 400 mcg per day is recommended, starting at least one month before conception). Nearly all multiple vitamins contain this amount of folic acid or more. It is also an opportunity to discuss how pregnancy may affect diabetes and vice versa.
Care during pregnancy is a team effort involving an obstetrician and an endocrinologist or primary care provider who oversees insulin management and medical care. Individuals can also be cared for by maternal fetal medicine specialists (high-risk obstetricians) with specialized training in managing diabetes in pregnancy.
Eye examination — Retinopathy refers to abnormal, leaky blood vessels in the light sensitive tissue lining the back of the eye (the retina). Retinopathy can lead to vision problems and even blindness in severe cases.
Pregnancy can worsen diabetic retinopathy. The risk of worsening retinopathy during pregnancy is increased in those with the highest initial glycated hemoglobin (A1C) values and in individuals whose A1C falls rapidly during pregnancy.
The impact of pregnancy on diabetic retinopathy is mild and temporary for most individuals; the retina usually returns to its prepregnancy condition within several months after giving birth. Nevertheless, all individuals with type 1 or 2 diabetes should have a dilated eye examination by an ophthalmologist or optometrist before pregnancy and during the first trimester (first three months of pregnancy). In some cases, a follow-up examination is recommended every three months until delivery, depending on the results of the initial examination.
Individuals with severe retinopathy are more likely to experience progression and complications. Eye examinations before and during pregnancy, along with close monitoring and treatment (as needed) of retinopathy can minimize the risk of vision loss. Some experts have recommended cesarean birth for individuals with proliferative retinopathy, but this is controversial; most individuals can attempt a vaginal birth.
Blood pressure monitoring — Blood pressure may become elevated during pregnancy and should be measured at every appointment. High blood pressure often improves during the first half of pregnancy but returns to baseline or worsens in the second half.
Medications to treat high blood pressure during pregnancy may include methyldopa, calcium channel blocking agents, hydralazine, or beta blockers. Most individuals can achieve adequate blood pressure control with a calcium channel blocker or beta blocker. Beta blockers can mask some symptoms of low blood glucose and should be used with caution.
Angiotensin-converting enzyme (ACE) inhibitors (captopril, lisinopril, enalapril) and angiotensin II receptor blockers (ARBs) (losartan, valsartan) are not safe for the fetus and should be discontinued in any patient planning pregnancy. If not discontinued before pregnancy, these drugs should be discontinued as soon as pregnancy is detected. An alternative, safer medication often needs to be substituted for the ACE or ARB.
High blood pressure complications — Pregnancy-related hypertension (preeclampsia, gestational hypertension) is more common in individuals with diabetes. Fortunately, most cases are mild. In severe cases, seizure, stroke, heart failure, kidney damage, and, rarely, maternal death can occur. (See "Patient education: Preeclampsia (Beyond the Basics)".)
Individuals with preexisting diabetes are asked to take low-dose aspirin (81 mg) daily, starting at the beginning of the second trimester (by 16 weeks of gestation) to decrease the chance of developing preeclampsia.
Kidney function monitoring — Pregnancy does not cause diabetes-related kidney disease (called diabetic nephropathy), but it can worsen existing disease. Kidney function is monitored during pregnancy by testing urine for the amount of protein excreted and testing blood for the creatinine level.
Diabetic nephropathy may increase the risk of developing other pregnancy complications, such as preeclampsia, preterm delivery, and babies who are small for their age (growth restriction). Individuals with these complications have a higher frequency of hospitalization during pregnancy and cesarean birth. Individuals with retinopathy and kidney disease are at increased risk of having a small baby because blood flow to the placenta may be reduced.
If an individual develops worsening nephropathy during pregnancy, it is usually temporary and reverts to the prepregnancy condition within several months of delivery. Nephropathy probably worsens because blood flow through the kidney increases by 50 percent during pregnancy, which increases the kidneys' workload. In addition, some individuals develop new pregnancy-induced high blood pressure, which further stresses the kidney.
Permanent kidney damage, including kidney failure, can occur in individuals who already have significant nephropathy before becoming pregnant. These individuals may require dialysis or kidney transplant sooner than an individual with severe chronic kidney disease who never becomes pregnant. (See "Patient education: Dialysis or kidney transplantation — which is right for me? (Beyond the Basics)" and "Patient education: Hemodialysis (Beyond the Basics)".)
Ultrasound — Ultrasound is recommended for several reasons during pregnancy.
To determine the due date — An ultrasound examination of the baby is recommended during the first trimester of pregnancy (the first 13 weeks of pregnancy) if there is any uncertainty about the date of the last menstrual period. It is important that the due date is accurate because decisions about when to begin fetal testing and when to deliver the baby are based upon this date.
To screen for congenital anomalies — Congenital anomalies are more common in infants of individuals with high blood glucose levels before pregnancy and during the early weeks of pregnancy; most congenital anomalies develop by the 10th week of pregnancy. Ultrasound examination is recommended at 18 to 20 weeks of gestation to screen for fetal anomalies. The examination should pay particular attention to the spine and heart because these are the sites of the most common congenital anomalies in infants of diabetic mothers; however, congenital anomalies in other organ systems also occur. In many cases, the individual is asked to get a specialized ultrasound examination of the fetal heart called a fetal echocardiogram.
To monitor amniotic fluid levels — Ultrasound is also used to monitor the amount of amniotic fluid around the fetus; polyhydramnios is an abnormal increase in the amount of amniotic fluid. Polyhydramnios is more common in individuals with diabetes than in those without diabetes. Polyhydramnios related to diabetes is usually mild and does not cause problems. If the fluid levels become severely elevated, maternal discomfort, uterine contractions, prelabor rupture of the membranes ("breaking the water"), and preterm birth can occur. (See "Patient education: Preterm labor (Beyond the Basics)".)
To monitor the baby's growth — Ultrasound is also used to monitor the baby's growth and development throughout the pregnancy, although ultrasound estimates of the baby's weight can be off by 15 percent or more.
Macrosomia is a condition in which a baby weighs much more than average. It is more common in infants of individuals with diabetes and occurs in 15 to 45 percent of these pregnancies. High fetal insulin levels, which can develop in response to elevated maternal blood glucose levels, are one potential cause of macrosomia since insulin stimulates fetal growth.
Cesarean birth may be needed if labor does not progress normally because of the large size of the baby. In addition, macrosomic babies are at higher risk of being injured during birth and may be delivered by cesarean birth before labor if there is a concern that the baby's shoulders may be difficult to deliver through the mother's pelvis (called shoulder dystocia) (see 'Planning for delivery' below). Shoulder dystocia occurs in one out of four macrosomic births in individuals with diabetes.
Fetal growth restriction refers to a baby that is not as large as expected for its age. It may be defined as birth weight <10th percentile weight for gestational age and is less common than macrosomia in pregnancies with diabetes. Individuals with type 1 diabetes with preexisting microvascular complications or hypertension have a higher risk of growth restriction, compared with those without preexisting vascular disease.
Screening for Down syndrome — Individuals with diabetes do not have a higher risk of having a baby with a chromosomal abnormality, such as Down syndrome, than those without diabetes. The risk of having a baby with Down syndrome primarily depends on the mother's age and whether there is a family history of Down syndrome. (See "Patient education: Should I have a screening test for Down syndrome during pregnancy? (Beyond the Basics)".)
Fetal testing — Close fetal monitoring is recommended during the third trimester, usually starting at 32 to 34 weeks of pregnancy. This usually includes weekly to twice weekly nonstress testing. This is done by monitoring the baby's heart rate with a small device that is placed on the mother's abdomen. The device uses sound waves (ultrasound) to measure the baby's heart rate over time, usually for 20 to 30 minutes.
Normally, the baby's baseline heart rate should be between 110 and 160 beats per minute and should increase above its baseline by at least 15 beats per minute for 15 seconds when the baby moves.
The test is considered reassuring (called "reactive") if two or more fetal heart rate increases are seen within a 20-minute period. Further testing may be needed if these increases are not seen after monitoring for 40 minutes.
Sometimes ultrasound is used to monitor fetal well-being. This test is called a biophysical profile and uses ultrasound to check the baby's amniotic fluid volume, number of body movements, tone, and duration of breathing-type movements. Some practitioners use a so-called "modified biophysical profile," consisting of a nonstress test and amniotic fluid assessment. The amniotic fluid assessment is performed by measuring pockets of fluid in four different areas or quadrants of the uterus.
PLANNING FOR DELIVERY — An individual and their obstetrician may decide to schedule the date of the birth (either an induction of labor or cesarean birth), especially if there are risk factors for an adverse maternal or fetal outcome, such as increased blood glucose levels, nephropathy, worsening retinopathy, high blood pressure or preeclampsia, or if the baby is smaller or larger than normal.
If the fetus appears to be very large (based upon ultrasound measurements), the individual and their obstetrician may consider cesarean birth to avoid possible trauma from shoulder dystocia. The American College of Obstetricians and Gynecologists (ACOG) suggests that an individual and their physician consider a planned cesarean birth if the baby's estimated weight (by ultrasound measurement) is greater than 4500 grams (9 lbs, 14 oz). (See "Patient education: C-section (cesarean delivery) (Beyond the Basics)".)
Waiting for labor to start on its own is reasonable if blood glucose levels are well controlled and the mother and baby are doing well. However, extending pregnancy beyond the 40th completed week of gestation is generally not recommended; some practitioners routinely induce labor between 39 weeks plus 0 days and 40 weeks plus 0 days in all individuals with type 1 or 2 diabetes.
During labor, blood glucose levels are checked frequently and insulin is given, as needed, to maintain good glucose control. Goals for blood glucose levels during labor are 80 to 120 mg/dL. Obstetricians will review the plan for blood glucose monitoring and insulin administration on an individualized basis.
The risk of stillbirth for individuals with well-controlled diabetes is very low and is approximately the same as in individuals without diabetes (less than 1 percent). The mortality (death) rate in infants of diabetic mothers is slightly higher than in those without diabetes (2 versus 1 percent). This is mostly due to a higher rate of serious congenital anomalies in infants of diabetic mothers.
Newborn issues — The infant of the diabetic mother is at risk for several problems in the newborn period, such as low blood glucose levels, jaundice, breathing problems, excessive red blood cells (polycythemia), low calcium level, and heart problems. These problems are more common when the mother's blood glucose levels have been high throughout the pregnancy. Most of these problems resolve within a few hours or days after birth. Infants of diabetic mothers are often evaluated in a special care nursery to monitor for these potential problems.
Infants of mothers with diabetes are at higher risk of having difficulties with breathing, especially if the baby is born earlier than 39 weeks. This is because the lungs appear to develop more slowly in infants of mothers with diabetes. The risk of breathing problems is highest when maternal blood glucose levels have been high near the time of delivery.
Will my child develop diabetes? — The children of parents with diabetes are at increased risk of developing the same type of diabetes. According to the American Diabetes Association (ADA):
●Children of a father with type 1 diabetes have a 1 in 17 risk of developing type 1 diabetes. Children of a mother with type 1 diabetes have a 1 in 25 risk if, at the time of pregnancy, the mother is less than 25 years of age. The risk is 1 in 100 risk if the mother is 25 years of age or older. These risks are doubled if the affected parent developed diabetes before age 11. If both parents have type 1 diabetes, the child's risk is 1 in 4 to 10 (10 to 25 percent risk).
●The risk of type 2 diabetes is increased in children of a parent with type 2 diabetes, especially if both parents are affected. The risk depends upon environmental and behavioral factors, such as obesity and sedentary lifestyle, as well as the genetic susceptibility. (See "Patient education: Type 1 diabetes: Overview (Beyond the Basics)" and "Patient education: Type 2 diabetes: Overview (Beyond the Basics)".)
AFTER DELIVERY CARE — Postpartum (after delivery) care of an individual with diabetes is similar to that of those without diabetes. However, it is important to pay close attention to blood glucose levels because insulin requirements can fall rapidly in the first few days after delivery; some individuals require little or no insulin. Insulin requirements usually return to near-prepregnancy levels within 48 hours.
Breastfeeding — In all postpartum individuals (with and without diabetes), breastfeeding is strongly encouraged because it benefits both the infant and the mother. Insulin requirements may be lower while breastfeeding, and frequent blood glucose monitoring is important to prevent severe hypoglycemia. (See "Patient education: Deciding to breastfeed (Beyond the Basics)" and "Patient education: Breastfeeding guide (Beyond the Basics)".)
Contraception — Individuals with diabetes who have no or minimal vascular disease may use any type of contraception, including oral contraceptive pills. Birth control pills do not affect blood glucose levels.
WHERE TO GET MORE INFORMATION — Your health care provider is the best source of information for questions and concerns related to your medical problem.
This article will be updated as needed on our website (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for health care professionals, are also available. Some of the most relevant are listed below.
Patient level information — UpToDate offers two types of patient education materials.
The Basics — The Basics patient education pieces 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.
Patient education: Care during pregnancy for people with type 1 or type 2 diabetes (The Basics)
Patient education: How to plan and prepare for a healthy pregnancy (The Basics)
Patient education: Preparing for pregnancy when you have diabetes (The Basics)
Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.
Patient education: Gestational diabetes (Beyond the Basics)
Patient education: Type 1 diabetes: Insulin treatment (Beyond the Basics)
Patient education: Glucose monitoring in diabetes (Beyond the Basics)
Patient education: Hypoglycemia (low blood glucose) in people with diabetes (Beyond the Basics)
Patient education: Preeclampsia (Beyond the Basics)
Patient education: Dialysis or kidney transplantation — which is right for me? (Beyond the Basics)
Patient education: Hemodialysis (Beyond the Basics)
Patient education: Preterm labor (Beyond the Basics)
Patient education: Should I have a screening test for Down syndrome during pregnancy? (Beyond the Basics)
Patient education: Amniocentesis (Beyond the Basics)
Patient education: C-section (cesarean delivery) (Beyond the Basics)
Patient education: Type 1 diabetes: Overview (Beyond the Basics)
Patient education: Type 2 diabetes: Overview (Beyond the Basics)
Patient education: Deciding to breastfeed (Beyond the Basics)
Patient education: Breastfeeding guide (Beyond the Basics)
Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.
Pancreas-kidney transplantation in diabetes mellitus: Benefits and complications
General principles of insulin therapy in diabetes mellitus
Pregestational (preexisting) diabetes mellitus: Antenatal glycemic control
Infants of mothers with diabetes (IMD)
Nutrition in pregnancy: Dietary requirements and supplements
Pregestational (preexisting) diabetes mellitus: Obstetric issues and management
Exercise during pregnancy and the postpartum period
Gestational diabetes mellitus: Screening, diagnosis, and prevention
Gestational diabetes mellitus: Glucose management and maternal prognosis
Pregestational (preexisting) diabetes: Preconception counseling, evaluation, and management
The following organizations also provide reliable health information.
●National Library of Medicine
(www.nlm.nih.gov/medlineplus/diabetesandpregnancy.html, available in Spanish)
●National Institute of Diabetes and Digestive and Kidney Diseases
●American Diabetes Association (ADA)
●The Endocrine Society
●Hormone Health Network
(www.hormone.org, available in Spanish)
ACKNOWLEDGMENT — The editorial staff at UpToDate would like to acknowledge John Repke, MD, who contributed to an earlier version of this topic review.
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