INTRODUCTION — The management of pregnancies after resolution of a suspected episode of acute idiopathic preterm labor (PTL) lacks high quality evidence on which to base recommendations. No large randomized trials have compared combinations of management strategies.
This topic will present our approach to management of patients who do not give birth and do not have advanced cervical dilation after resolution of an acute episode of suspected idiopathic PTL. The evaluation and management of patients with suspected acute PTL are discussed separately. (See "Preterm labor: Clinical findings, diagnostic evaluation, and initial treatment" and "Inhibition of acute preterm labor".)
OUR APPROACH
Antenatal corticosteroids — Pregnancies from 22+0 to 33+6 weeks of gestation predicted to be at increased risk for preterm birth in the next seven days are candidates for an initial course of antenatal corticosteroids to reduce neonatal morbidity and mortality if preterm birth occurs. Administration of an initial course of antenatal corticosteroids at 34+0 to 36+6 weeks of gestation is controversial; however, there is consensus that tocolysis should not be used to delay delivery for completion of a course of steroids at this gestational age. The use of antenatal corticosteroids at various gestational ages and the indications for rescue/salvage/booster therapy in patients who have received an initial course of therapy are discussed in detail separately. (See "Antenatal corticosteroid therapy for reduction of neonatal respiratory morbidity and mortality from preterm delivery".)
Continuation of progesterone supplementation — For patients who had been receiving supplemental vaginal progesterone to reduce the risk of preterm birth because of a short cervix on ultrasound examination, we continue their same progesterone dose after resolution of an episode of suspected PTL.
We would not newly initiate progesterone supplementation in patients who were not candidates for therapy before their episode of PTL. (See 'Initiation of progesterone supplementation' below.)
Duration of hospitalization — After resolution of an episode of suspected acute PTL with intact membranes, we consider several factors when determining the duration of hospitalization.
●Patients who are ≥34 weeks of gestation with suspected acute PTL generally do not receive tocolytic therapy because 34 weeks defines the threshold at which perinatal morbidity and mortality are too low to justify the potential maternal and fetal complications and costs associated with inhibition of PTL and short-term delay of delivery (see "Inhibition of acute preterm labor", section on 'Lower and upper gestational age limits'). However, they may receive a course of antenatal corticosteroid therapy; practice at this gestational age varies and is reviewed separately. (See "Antenatal corticosteroid therapy for reduction of neonatal respiratory morbidity and mortality from preterm delivery", section on '34+0 or more weeks'.)
These patients can be discharged when the episode of suspected PTL resolves, as long as tests of fetal well-being are reassuring (reactive nonstress test or good biophysical profile score) and no additional complications are present that warrant hospitalization (eg, fever, abruption, preterm prelabor rupture of membranes, pregnancy-related hypertension).
For patients with advanced cervical dilation/effacement and/or a history of rapid labor, the travel time to a hospital with appropriate levels of obstetric and neonatal care services needs to be considered. Many of these patients will need to remain in the hospital because of the risk of giving birth in a less than optimal setting if they are discharged.
●For patients <34 weeks of gestation with suspected acute PTL, we base the duration of hospitalization on patient-specific factors, including gestational age, cervical status, past obstetric history, distance between their residence and the hospital, and coexisting obstetric and medical problems [1,2]. Patients who receive antenatal corticosteroids generally remain in the hospital until the course has been completed (eg, 24 hours after the second dose of betamethasone), but this decision can be individualized.
The only randomized trial designed to determine whether hospitalization of patients after resolution of an episode of PTL increased the proportion of births ≥36 weeks compared with patients discharged home did not find a benefit [3]. In this trial, 101 participants with singleton gestations, intact membranes, mean cervical dilation 2.7 cm, and a diagnosis of arrested PTL between 24+0 and 33+4 weeks of gestation were randomly assigned to hospitalization until 34+0 weeks or discharged home upon completion of a course of dexamethasone. Tocolytics were not administered; contractions ceased with conservative management alone (hydration, meperidine). In both groups, approximately 70 percent of participants gave birth at ≥36 weeks of gestation. However, the trial was underpowered, and the findings are not generalizable to the more clinically relevant population of patients with arrested PTL after tocolytic therapy [4].
Outpatient follow-up — We schedule an office visit or telephone/telemedicine contact one week after discharge from the hospital and usually weekly thereafter for both singleton and twin pregnancies. These visits provide an opportunity to discuss signs and symptoms of PTL and to check for cervical change in the absence of symptoms that may warrant a change in management. For example, a patient whose cervix was 2 cm dilated on hospital discharge at 25 weeks but 4 cm dilated on follow-up at 28 weeks may be a candidate for a rescue course of steroids. (See "Antenatal corticosteroid therapy for reduction of neonatal respiratory morbidity and mortality from preterm delivery", section on 'Use of rescue (salvage, booster) ACS'.)
In patients who remain stable and have a closed, uneffaced cervix, it may be safe to resume the usual frequency of prenatal care visits. No data are available.
Physical activity
Activities of daily life — We advise patients that they may resume most activities of daily living and also advise avoiding daytime bed rest given the lack of evidence of its efficacy for reduction of preterm birth and the known significant thromboembolic and other risks of prolonged immobility [5]. We suggest against lifting anything greater than 20 pounds, based on longstanding practice patterns.
A trial of 120 with arrested at 24 to 34 weeks with <3 cm, 48 hours of hospitalization, and ≤25 mm found that activity restriction (pelvic rest, prohibition of sexual activity, and reduction of work and/or nonwork activity) did not reduce the risk of preterm birth <37 weeks compared with no activity restriction (25 versus 38 percent; RR 0.65, 95% CI 0.38-1.12) [6]. A systematic review found inadequate evidence either supporting or refuting the use of bed rest at home or in-hospital to prevent preterm birth in singleton gestations at high risk of preterm birth (1 trial, >1200 participants) [7]. Another systematic review found inadequate evidence to support a policy of routine hospitalization for bed rest in multiple gestations (7 trials, >700 participants) [8]. On the other hand, there is clear evidence that bed rest has potential harms: It increases venous thromboembolism risk, promotes loss of trabecular bone density and musculoskeletal deconditioning, and places significant psychosocial strain on individuals and families [9-16].
Exercise — We agree with the general consensus that pregnant patients at high risk for preterm birth should limit recreational exercise, particularly strength training and heavy lifting (>20 pounds) [17,18]. This is a prudent approach because most trials of recreational exercise in pregnancy have excluded those at increased risk for PTL or those who developed PTL during the trial; therefore, it is difficult to assess the effect of recreational exercise on pregnancy outcome in these individuals. (See "Exercise during pregnancy and the postpartum period" and "Spontaneous preterm birth: Overview of risk factors and prognosis".)
Work — We suggest that patients at high risk for preterm birth avoid returning to work if this involves working more than 40 hours per week, night shifts, prolonged standing (eg, more than a total of 8 hours or more than 4 continuous hours per 24-hour period), and heavy physical work, as this activity level has been variably associated with PTL and preterm birth [19-22]. However, the effect of occupational work on preterm birth is difficult to analyze because occupational activities are complex constructs involving duration of work, shift effects, psychological and physical stress, lifting (frequency and amount of weight), length of time standing, etc, and thus cannot readily be characterized in a simple way. (See "Working during pregnancy" and "Spontaneous preterm birth: Overview of risk factors and prognosis".)
Sexual intercourse — We tell patients with an arrested episode of PTL that they should consider avoiding sexual intercourse if they experience an increased frequency or intensity of contractions afterward. There is no strong evidence that sexual activity affects the risk of preterm birth or onset of labor in healthy individuals. However, it is theoretically possible that a small subgroup of susceptible individuals may develop PTL with sexual intercourse because both prostaglandins in semen and orgasm can increase myometrial activity [23-26]. (See "Spontaneous preterm birth: Overview of risk factors and prognosis", section on 'Role of coitus'.)
Travel — It is unlikely that car, train, or even airline travel significantly increases the risk of PTL or preterm birth; however, patients who wish to travel need to consider the risk of pregnancy complications away from their usual source of medical care, as well as the availability of medical resources and their medical insurance coverage at their destination [27-30]. (See "Prenatal care: Patient education, health promotion, and safety of commonly used drugs", section on 'Travel'.)
INEFFECTIVE AND UNPROVEN INTERVENTIONS
Maintenance tocolysis — After acute inhibition of PTL, meta-analyses of randomized trials have consistently found that, compared with placebo/no treatment, maintenance tocolysis with nifedipine, terbutaline (orally or via pump), or magnesium sulfate did not result in statistically significant prolongation of pregnancy, reduction of preterm birth, or improvement in neonatal outcome [31-34]. However, most trials were small and had study design limitations. Tocolytic drugs may have a role in providing symptomatic relief with respect to intensity and frequency of contractions, but the risk of serious adverse events, especially with prolonged terbutaline pump or magnesium sulfate therapy, outweighs any potential benefit [35-37].
A randomized trial in over 500 patients that compared atosiban (an oxytocin antagonist) with placebo for maintenance therapy after an episode of PTL also found that active therapy did not result in statistically significant reductions in preterm birth before 28, 32, or 37 weeks of gestation, although the time to first recurrence of labor was prolonged (33 days with atosiban versus 28 days with placebo) [38,39].
Antibiotic prophylaxis — There is no convincing evidence of benefit from prophylactic antibiotic therapy for patients with PTL with intact membranes and no evidence of infection. In a meta-analysis of randomized trials of asymptomatic, nonlaboring participants at high risk of preterm birth assigned to prophylactic antibiotic therapy or placebo, antibiotic therapy did not result in statistically significant reductions in preterm birth, irrespective of criteria used to assess risk, the antimicrobial agent administered, or the gestational age at the time of treatment [40]. A subsequent meta-analysis of trials of routine antibiotic prophylaxis in different types of pregnant patients (eg, unselected patients, patients at high risk of preterm birth by past histories, patients who were predominantly HIV positive) affirmed these findings [41].
Although group B Streptococcus (GBS) chemoprophylaxis is recommended for patients with active PTL, it is discontinued once the patient is no longer at imminent risk of preterm birth, even if the GBS rectovaginal culture is positive, as continued therapy is not beneficial. Guidelines for GBS prophylaxis are reviewed separately. (See "Prevention of early-onset group B streptococcal disease in neonates", section on 'Special populations'.)
Initiation of progesterone supplementation — For patients who were not candidates for vaginal progesterone supplementation before their episode of suspected PTL, we do not begin vaginal progesterone as an adjunct to tocolysis or as part of maintenance therapy after resolution of the episode, regardless of cervical length, because available data suggest that it is not beneficial.
Randomized trials evaluating various types of progesterone supplementation in this setting have reported disparate results, likely related to factors such as differences in size, type of progestin, route of administration, and inclusion of a placebo versus a no treatment arm. In a meta-analysis of randomized trials, maintenance progesterone (vaginal, intramuscular, or oral) was not more effective than placebo [42]:
●Delivery <37 weeks – RR 0.94 (95% CI 0.80-1.10; 11 trials)
●Delivery <34 weeks – RR 0.87 (95% CI 0.66-1.15; 9 trials)
●No statistically significant difference in neonatal sepsis, necrotizing enterocolitis, intraventricular hemorrhage, admission to neonatal intensive care unit (NICU), respiratory distress syndrome, or neonatal death
Cervical pessary — The first clinical trial to evaluate use of a cervical pessary versus routine care in patients with singleton pregnancies and short cervical length after an episode of arrested PTL reported a trend in reduction in spontaneous preterm birth <34 weeks (10.7 versus 13.7 percent with routine care, relative risk [RR] 0.78, 95% CI 0.45-1.38) and statistically significant reductions in spontaneous preterm birth <37 weeks (14.7 versus 25.1 percent, RR 0.58, 95% CI 0.38-0.90) and preterm prelabor rupture of membranes (2.3 versus 8.0 percent, RR 0.28, 95% CI 0.09-0.84); however, neonatal morbidity and mortality were similar in both groups [43]. These results are promising, but the number of spontaneous preterm births in the trial was relatively small (43 <34 weeks, 70 <37 weeks). A subsequent smaller trial, which was halted early for futility, observed no reduction in preterm birth <32, 34, or 37 weeks [44].
The major side effect of using a pessary is vaginal discharge, which occurs in most patients. No serious side effects have been reported [45,46]. Nevertheless, until a benefit in neonatal outcome is established, we suggest only utilizing pessaries in the context of a clinical trial. (See "Cervical insufficiency", section on 'Pessary'.)
Antepartum fetal surveillance — After resolution of an episode of suspected PTL, we do not perform antenatal fetal assessment (nonstress tests, biophysical profile) or serial ultrasound examinations for fetal growth assessment unless a standard medical or obstetric indication exists for these tests. PTL alone is not an indication for antepartum fetal surveillance since the risk of fetal demise is not increased in this setting. (See "Overview of antepartum fetal assessment".)
Fetal fibronectin testing — We do not use fetal fibronectin (fFN) testing to monitor asymptomatic patients who are clinically stable after an episode of acute PTL, whether or not they have had a previous fFN test. There are no studies on the use of fFN testing after an episode of PTL to further stratify preterm birth risk status and guide management. (See "Preterm labor: Clinical findings, diagnostic evaluation, and initial treatment", section on 'Fetal fibronectin for selected patients'.)
Home uterine activity monitoring — We agree with the American College of Obstetricians and Gynecologists and other expert organizations that recommend not using home uterine activity monitors to monitor patients at increased risk for PTL or recurrent PTL [47,48]. In a meta-analysis of trials of standard care "with" versus "without" home uterine activity monitoring, the intervention had no significant impact on maternal and perinatal outcomes such as perinatal mortality (RR 1.22, 95% CI 0.86-1.72, two trials, 2589 newborns) or preterm birth (average RR 0.85, CI 0.72-1.01, eight trials, 4834 participants) [49].
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: Preterm labor and birth".)
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 5th to 6th 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 10th to 12th 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.)
●Beyond the Basics topics (see "Patient education: Preterm labor (Beyond the Basics)")
SUMMARY AND RECOMMENDATIONS
●Antenatal corticosteroids – Patients at 23+0 to 33+6 weeks of gestation anticipated to be at increased risk for preterm birth in the next seven days should receive an initial course of antenatal corticosteroids.
Administration of an initial course at 34+0 to 36+6 weeks is controversial; however, there is consensus that tocolysis should not be used to delay delivery for completion of a course of steroids at this gestational age.
The indications for rescue/salvage/booster therapy are discussed in detail separately. (See "Antenatal corticosteroid therapy for reduction of neonatal respiratory morbidity and mortality from preterm delivery".)
●Supplemental progesterone – For patients with a short cervix who were receiving vaginal progesterone for prevention of preterm birth, we continue their same progesterone regimen after resolution of an episode of suspected preterm labor (PTL). (See 'Continuation of progesterone supplementation' above.)
We suggest not newly initiating progesterone therapy as an adjunct to tocolysis or as part of maintenance therapy after a resolved episode of PTL (Grade 2C). Treatment does not appear to be effective in this setting. (See "Progesterone supplementation to reduce the risk of spontaneous preterm labor and birth", section on 'Maintenance therapy after threatened preterm labor'.)
●Duration of hospitalization – Many patients who are stable after an episode of PTL can be managed as outpatients, as long as tests of fetal well-being are reassuring and no additional obstetric/medical complications are present that warrant hospitalization. For patients with advanced cervical dilation/effacement and/or a history of rapid labor, the travel time to a hospital with appropriate levels of obstetric and neonatal care services needs to be considered. (See 'Duration of hospitalization' above.)
●Outpatient follow-up – We schedule an office visit or telephone/telemedicine contact one week after the patient leaves the hospital and usually weekly thereafter to check for symptoms of recurrent PTL and asymptomatic cervical dilation/effacement. We do not perform antenatal fetal surveillance testing unless a standard indication exists for these tests. PTL alone is not an indication for antepartum fetal surveillance since the risk of fetal demise is not increased. (See 'Outpatient follow-up' above and 'Antepartum fetal surveillance' above.)
●Activity
•We do not advise bed rest for patients with a recent episode of PTL given the lack of evidence of efficacy for prolonging gestation or reducing preterm birth and the known significant risks of prolonged immobility. They may continue typical activities of daily living.
We agree with the general consensus that patients at high risk for preterm birth should limit recreational exercise and avoid returning to work if their work involves working more than 40 hours per week, night shifts, prolonged standing, or heavy physical work (eg, lifting ≥20 pounds), as this activity level has been variably associated with PTL and preterm birth. (See 'Activities of daily life' above and 'Exercise' above and 'Work' above.)
•We advise patients with a resolved episode of PTL that they should consider avoiding sexual activity if they experience an increased frequency or intensity of contractions after sexual intercourse. (See 'Sexual intercourse' above.)
●Travel – It is unlikely that travel significantly increases the risk of PTL or preterm birth; however, patients who wish to travel need to consider the risk of pregnancy complications away from their usual source of medical care, the availability of medical resources, and their medical insurance coverage at their destination. (See 'Travel' above.)
●Ineffective and unproven interventions
•Maintenance tocolysis, antibiotic prophylaxis, home uterine monitoring, and fibronectin testing do not improve outcomes after an episode of arrested PTL. (See 'Ineffective and unproven interventions' above.)
•In patients with a short cervix after an episode of PTL, neither a benefit nor serious harm from use of a cervical pessary has been established. We suggest only utilizing pessaries in this setting in the context of a clinical trial. (See 'Cervical pessary' above.)
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