Maternal Activity Restriction in Pregnancy and the Prevention of Preterm Birth: An Evidence-based Review

Activity restriction and risk of adverse pregnancy outcomes

BACKGROUND

Activity restriction is a common recommendation given to patients during pregnancy for various indications, despite lack of definitive data showing improvements in pregnancy outcomes.

OBJECTIVE

To determine if activity restriction (AR) in pregnancy is associated with decreased odds of adverse pregnancy outcomes (APOs).

STUDY DESIGN

Secondary analysis of the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-Be (nuMoM2b) prospective cohort. Nulliparous singletons were followed at 8 sites from October 2010-September 2013. Demographic and clinical data were collected at 4 timepoints, and participants were surveyed about AR recommendations at 22w0d-29w6d and delivery. We excluded participants missing data on AR and age. Participants were grouped according to history of AR, and APOs included: gestational hypertension (gHTN), preeclampsia/eclampsia, preterm birth (PTB), and small for gestational age (SGA) neonate. Associations between AR and APOs were examined using uni- and multivariable logistic regression models adjusting for a priori identified APO risk factors.

RESULTS

Of 10,038 nuMoM2b participants, 9,312 met inclusion criteria and 1,386 (14.9%) were recommended AR; participants identifying as Black (aOR 0.81 [95% CI 0.68-0.98]) or Hispanic (aOR 0.73 [95% CI 0.61-0.87]) were less likely to be placed on AR when compared to those identifying as White. Overall, 3,197 (34.3%) experienced at least one APO (717 [51.7%] of participants with AR compared to 2,480 [31.3%] participants without AR). After adjustment for baseline differences, the AR group had increased odds of gHTN (aOR 1.61 [95% CI 1.35-1.92]), preeclampsia/eclampsia (aOR 2.52 [95% CI 2.06-3.09]) and iatrogenic and spontaneous PTB (aOR 2.98 [95% CI 2.41-3.69]), but not delivery of an SGA neonate.

CONCLUSION

AR in pregnancy was independently associated with increased odds of hypertensive disorders of pregnancy and PTB, but future prospective work is needed to determine potential causality. Further, participants identifying as Black or Hispanic were significantly less likely to be recommended AR compared to those identifying as White. While AR is not an evidence-based practice, these findings suggest bias may impact which patients receive advice to limit activity in pregnancy. El resumen está disponible en Español al final del artículo.

Impact of Physical Activity Interventions on High-Risk Pregnancies: A Systematic Review and Meta-Analysis

Pregnant women with absolute contraindications may be advised against physical activity throughout pregnancy. In this context, bed rest elevates the short-term risk of neonatal complications, thereby exacerbating negative long-term effects on childhood development. The aim of the current study was to investigate the impact of various physical activity interventions during bed rest or activity restriction in pregnancy on factors such as birth weight, preterm birth, maternal hypertension, gestational age at delivery, and the incidence of cesarean sections. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic review was designed. The protocol was registered in the International Prospective Registry of Systematic Reviews (PROSPERO) (CRD42022370875). Nine studies, with a total sample of 3173 women, from six countries on four continents were included. There were significant differences in the relationship between bed rest status and birth weight (Z = 2.64; p = 0.008) (MD = 142.57, 95% CI = 36.56, 248.58, I2 = 0%, Pheterogeneity = 0.45) favourable to active groups. No significant differences were found in other analyzed outcomes. Pregnant women who experience this problem must maintain a minimum of daily activity to alleviate these physiological complications and the medical field must understand the consequences of physical inactivity during pregnancy.

Maintenance tocolysis, tocolysis in preterm premature rupture of membranes and in cervical cerclage - a Germany-wide survey on the current practice after dissemination of the German guideline

OBJECTIVES

To investigate the adherence of German perinatal specialist units and those of basic obstetric care to the national guideline we compared data from a nation-wide survey on the practice of maintenance tocolysis, tocolysis in preterm premature rupture of membranes and in the perioperative setting of cervical cerclage, and bedrest during and after tocolysis with recommendations from the current German Guideline 015/025 "Prevention and Treatment of Preterm Birth".

METHODS

632 obstetric clinics in Germany were approached and received a link to an online questionnaire. Data were descriptively analyzed by performing measures of frequency. To compare two or more groups Fisher's exact test was used.

RESULTS

The response rate was 19%; 23 (19.2%) of respondents did not perform maintenance tocolysis, while 97 (80.8%) conducted maintenance tocolysis; 30 (25.0%) of obstetric units performed cervical cerclage without tocolysis and 90 (75.0%) combined cervical cerclage with tocolysis; 11 (9.2%) of respondents did not use tocolytics in patients with preterm premature rupture of membranes, while 109 (90.8%) conducted tocolysis in these patients; 69 (57.5%) of obstetric units did not recommend bed rest during tocolysis, whereas 51 (42.5%) favored bedrest. Perinatal care centers of basic obstetric care recommend bed arrest during tocolysis statistically significant more often to their patients than those of higher perinatal care levels (53.6 vs. 32.8%, p=0.0269).

CONCLUSIONS

The results of our survey are in accordance to others from different countries and reveal considerable discrepancies between evidence-based guideline recommendations and daily clinical practice.

Perceived stress and support preferences during bed rest in twin pregnancies: A cross-sectional online survey

OBJECTIVE

To identify the most prominent sources of stress, examine correlates of stress, and assess support preferences to inform future interventions among women pregnant with twins who are on bed rest.

MATERIALS AND METHODS

A cross-sectional online survey was administered to pregnant and postpartum women who were recommended bed rest during their twin pregnancy. Total stress while on bedrest was assessed using an adapted version of the Antepartum Hospital Stressors Inventory (AHSI). Bivariate analyses were used to compare total stress scores across participant characteristics using linear regression, Spearman's correlation, and one-way ANOVA. Qualitative content regarding women's bed rest experiences and future intervention preferences was analyzed into themes.

FINDINGS

Women's (N = 104, mean age 30.6 years ± 4.6) most prominent sources of stress while on bed rest included thinking about babies' health, feeling dependent on others, and feeling uncertain about the outcome. Women who were recommended bed rest earlier in their pregnancy or were recommended both home and hospital bedrest had higher stress scores, while women with monochorionic/monoamniotic pregnancies had lower stress scores. Approximately 64% of women indicated interest in a bed rest support program, with 88% indicating a preference for online support and 70% wanting support from family.

KEY CONCLUSIONS

Women pregnant with twins who are recommended bed rest identify many sources of stress. Our findings suggest a need for stress-management interventions targeting this population.

Society for Maternal-Fetal Medicine Consult Series #50: The role of activity restriction in obstetric management: (Replaces Consult Number 33, August 2014)

Despite current recommendations against its use, activity restriction remains a common intervention used to prevent preterm birth in multiple clinical settings. Hypertensive disorders of pregnancy, preterm premature rupture of membranes, multiple gestations, vaginal bleeding, short cervical length, placenta previa, and fetal growth restriction are also common reasons for antepartum hospital admission and frequently lead to a recommendation for activity restriction. However, numerous reports have shown that activity restriction does not prevent adverse obstetrical outcomes but does confer significant physical and psychosocial risks. This consult reviews the current literature on activity restriction and examines the evidence regarding its use in obstetrical management. The recommendations by the Society for Maternal-Fetal Medicine are as follows: (1) we recommend against the routine use of any type of activity restriction in pregnant women at risk of preterm birth based on preterm labor symptoms, arrested preterm labor, or shortened cervix (GRADE 1B); (2) we recommend against the use of routine inpatient hospitalization and activity restriction for the prevention of preterm birth in women with multiple gestations (GRADE 1A); and (3) given the lack of data definitively demonstrating that activity restriction improves perinatal outcome in pregnancies complicated by fetal growth restriction, preterm premature rupture of membranes, or hypertensive diseases of pregnancy, coupled with evidence of adverse effects of activity restriction, we suggest that activity restriction not be prescribed for the treatment of pregnancies complicated by fetal growth restriction, preterm premature rupture of membranes, or hypertensive disease (GRADE 2B).

Maternal activity restriction to reduce preterm birth: Time to put this fallacy to bed

Activity restriction has traditionally been recommended to pregnant women, especially high-risk patients, to reduce preterm birth. However, there is no scientific evidence that bed-rest reduces preterm birth and, in many studies, women on bed-rest had higher rates of delivering preterm. Bed-rest in pregnancy is associated with significant physiological and psychosocial sequelae and reduced neonatal birth weight and be cannot be endorsed, even in women with a short cervix. The practice of prescribing bed-rest in pregnancy is outdated and should be abandoned.

Reducing the Risk of Preterm Birth by Ambulatory Risk Factor Management

BACKGROUND

The preterm birth rate in Germany has remained unchanged at 8-9% since 2009. Preterm birth is the most common cause of neonatal morbidity and mortality. In the absence of a causal treatment, it is important to lower the risk of preterm birth by preventive measures in prenatal outpatient care.

METHODS

This review is based on pertinent publications from the years 2000-2019 that were retrieved by a selective search in PubMed.

RESULTS

The clinical risk factors for preterm birth-known mainly from retrospective cohort studies-include previous preterm birth (adjusted odds ratio [aOR]: 3.6), multiple pregnancy (relative risk [RR]: 7.7), nicotine consumption (aOR: 1.7), and a short uterine cervix, i.e., <25 mm in the second trimester (aOR: 6.9). In women with a short cervix, vaginally administered progesterone significantly lowers the preterm birth rate (22.5% vs. 14.1% for birth before 33 weeks of gestation, RR: 0.62; 95% confidence interval [0.47; 0.81]). Nicotine abstinence is associated with a lower pre- term birth rate as well (aOR: 0.91; [0.88; 0,.94]), while working more than 40 hours per week (aOR: 1.25; [1,.01; 1,.54]) and heavy lifting during pregnancy (hazard ratio [HR]: 1.43; [1.13; 1.80]) are associated with a higher preterm birth rate. Avoidance of physical exertion, or bed rest, in the face of impending preterm birth does not lower the preterm birth rate, but it does increase the risk of complications, such as thromboembolism.

CONCLUSION

The meticulous assessment and elimination of treatable risk factors at the outset of ambulatory prenatal care can help lower the preterm birth rate. Further velopment of causally directed treat- ments (e.g., changes of relevant environmental and epigenetic factors).

Thromboprophylaxis in Pregnancy

Venous thromboembolism is a leading cause of maternal morbidity and mortality worldwide. Identifying women who are at greatest risk for venous thromboembolism, and managing their pregnancies with appropriate thromboprophylaxis is essential to decreasing this life-threatening condition. Those at greatest risk are patients with thrombophilias, a personal or family history of venous thromboembolism, and those undergoing cesarean delivery. Current international guidelines on thromboprophylaxis vary in details, but all strategies rely on risk factor identification and thromboprophylaxis for the highest risk patients. All guidelines require clinicians to think critically about individual patient's risk factors throughout pregnancy and the postpartum period.

Patterns of leisure-time physical activity across pregnancy and adverse pregnancy outcomes

Background

Although leisure-time physical activity (PA) contributes to overall health, including pregnancy health, patterns across pregnancy have not been related to birth outcomes. We hypothesized that women with sustained low leisure-time PA would have excess risk of adverse pregnancy outcomes, and that changing patterns across pregnancy (high to low and low to high) may also be related to risk of adverse pregnancy outcomes.

Methods

Nulliparous women (n = 10,038) were enrolled at 8 centers early in pregnancy (mean gestational age in weeks [SD] = 12.05 [1.51]. Frequency, duration, and intensity (metabolic equivalents) of up to three leisure activities reported in the first, second and third trimesters were analyzed. Growth mixture modeling was used to identify leisure-time PA patterns across pregnancy. Adverse pregnancy outcomes (preterm birth, [PTB, overall and spontaneous], hypertensive disorders of pregnancy [HDP], gestational diabetes [GDM] and small-for-gestational-age births [SGA]) were assessed via chart abstraction.

Results

Five patterns of leisure-time PA across pregnancy were identified: High (35%), low (18%), late decreasing (24%), early decreasing (10%), and early increasing (13%). Women with sustained low leisure-time PA were younger and more likely to be black or Hispanic, obese, or to have smoked prior to pregnancy. Women with low vs. high leisure-time PA patterns had higher rates of PTB (10.4 vs. 7.5), HDP (13.9 vs. 11.4), and GDM (5.7 vs. 3.1, all p < 0.05). After adjusting for maternal factors (age, race/ethnicity, BMI and smoking), the risk of GDM (Odds ratio 2.00 [95% CI 1.47, 2.73]) remained higher in women with low compared to high patterns. Early and late decreasing leisure-time PA patterns were also associated with higher rates of GDM. In contrast, women with early increasing patterns had rates of GDM similar to the group with high leisure-time PA (3.8% vs. 3.1%, adjusted OR 1.16 [0.81, 1.68]). Adjusted risk of overall PTB (1.31 [1.05, 1.63]) was higher in the low pattern group, but spontaneous PTB, HDP and SGA were not associated with leisure-time PA patterns.

Conclusions

Sustained low leisure-time PA across pregnancy is associated with excess risk of GDM and overall PTB compared to high patterns in nulliparous women. Women with increased leisure-time PA early in pregnancy had low rates of GDM that were similar to women with high patterns, raising the possibility that early pregnancy increases in activity may be associated with improved pregnancy health.

Trial registration

Registration number NCT02231398.

Electronic supplementary material

The online version of this article (10.1186/s12966-018-0701-5) contains supplementary material, which is available to authorized users.

Quantitative assessment of physical activity in pregnant women with sonographic short cervix and the risk for preterm delivery: A prospective pilot study

Objective

Bed rest or activity restriction is a common obstetrical practice, despite a paucity of data to support its efficacy. The aim of this study was to determine whether physical activity, as assessed by a smart band activity tracker, is associated with preterm birth in pregnant women at high risk for preterm delivery.

Methods

This was a pilot prospective cohort study including pregnant women at high risk for preterm delivery between 24 and 32 weeks-of-gestation. Physical activity level was assessed by smart band activity. Patients with sonographic short cervical length (≤ 20 mm) were asked to wear the smart band activity tracker continuously for at least one week, including one weekend. Both physicians and patients were blinded to the data stored in the smart band activity tracker. No specific recommendations were given to participants as to the level or intensity of physical activity. The primary outcome was the rate of preterm birth (< 37 weeks-of-gestation). Secondary outcomes included the rate of delivery before 34 weeks of gestation and neonatal outcome. Parametric and nonparametric statistics were used for analysis.

Results

Study population included 49 pregnant women: 37 women (75.7%) delivered preterm and 12 (24.5%) delivered at or after 37 weeks-of-gestation. The median steps per day was significantly lower in patients who delivered preterm (3576, IQR: 2478–4775 vs. 4554, IQR: 3632–6337, p = 0.02). Regression analysis revealed that the median number of steps per day was independently inversely associated with preterm birth, after adjustment for maternal age, body mass index, gestational age at recruitment, cervical length, cervical dilatation and plurality.

Conclusion

This pilot study represents the first quantitative assessment of the association between physical activity and preterm birth. The results of this pilot study do not support the efficacy of decreased physical activity in the prevention of preterm birth in patients with sonographic short cervical length.

Activity restriction and risk of preterm delivery. J Matern Fetal Neonatal Med 2017;31:2136-2140. [PMID: 28573877 DOI: 10.1080/14767058.2017.1337738]

PURPOSE

We sought to determine whether activity restriction (AR) in a cohort of women at high risk for preterm delivery is associated with the risk of preterm delivery.

MATERIALS AND METHODS

This is a secondary analysis of the Maternal-Fetal Medicine Units MFMU's Preterm Prediction Study; a multicenter prospective cohort study designed to identify risk factors of preterm birth (PTB). The study group consisted of women with a singleton gestation that at their first study visit (23-24 weeks) had at least one of the following criteria: patient reported contractions, severe back pain, a cervical length <15 mm, spotting, protruding membranes, or positive fetal fibronectin. Women were assessed for AR at a 27- to 29-week study visit. Associations between AR and preterm delivery (<37 weeks) were examined through logistic regression models before and after adjustment for confounders.

RESULTS

Of the 1086 women that met the inclusion criteria, 16.5% (n = 179) delivered preterm. In this cohort, 9.7% (n = 105) of women were recommended AR, with 37.1% (n = 39) having a PTB. In the group not recommended AR (n = 981), 14.3% (n = 140) delivered preterm.

CONCLUSION

In this cohort of women at high risk for PTB, activity restriction was associated with an increased risk of PTB. The use of AR in this population should be discouraged.