Bed rest in pregnancy: time to put the issue to rest

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.

Activity restriction for women with arrested preterm labor: a randomized controlled trial

BACKGROUND

In the past, some pregnant women have been recommended to be in activity restriction because of the presumed increased risk of preterm birth due to the increased release of catecholamines, which might stimulate myometrial activity, during exercise and aerobic activity.

OBJECTIVE

This study aimed to test the hypothesis that in women with singleton pregnancy and arrested preterm labor, activity restriction would reduce the rate of preterm birth at <37 weeks of gestation.

STUDY DESIGN

This was a parallel-group nonblinded randomized trial conducted at a single center in Italy. Eligible patients were those with a diagnosis of arrested preterm labor, defined as not delivering after 48 hours of hospitalization for threatened preterm labor, with transvaginal ultrasound cervical length ≤25 mm, no other symptoms of possible uterine contractions, and cervical dilatation <3 cm at pelvic examination. Inclusion criteria were singleton pregnancies between 24 0/7 and 33 6/7 weeks of gestation. Participants were randomized in a 1:1 ratio to either activity restriction at the time of discharge or no activity restriction. Women in the intervention group were recommended activity restriction, defined as the following: pelvic rest, prohibition of sexual activity, and reduction of work and/or nonwork activity. The primary endpoint was preterm birth at <37 weeks of gestation.

RESULTS

A total of 120 participants were included in the trial; 60 patients were enrolled in the activity restriction group and 60 in the control group. Preterm birth at <37 weeks of gestation occurred in 15 of 60 women (25.0%) in the activity restriction group and 23 of 60 women (38.3%) in the control group (relative risk, 0.65; 95% confidence interval, 0.38-1.12). There was no significant between-group difference in the incidence of preterm birth at <32 weeks and in neonatal outcomes, but the trial was not powered for these outcomes.

CONCLUSION

In singleton gestations with arrested preterm labor, activity restriction, including pelvic rest, prohibition of sexual activity, and reduction of work and/or nonwork activity, does not result in a lower rate of preterm birth at <37 weeks. Given the evidence on the lack of benefits, use of activity restriction in this population should be discouraged.

Adherence to recommended physical activity restrictions due to threatened preterm delivery - a descriptive multi-center study

BACKGROUND

Threatened preterm delivery is a serious obstetrical complication and has for decades been prescribed physical activity restrictions (AR). Adherence to the recommended level of physical AR is however unknown. This study aimed to assess the objectively measured different physical positions and activities of pregnant women recommended AR due to threatened preterm delivery complications, compared to a reference group of uncomplicated pregnant women without restrictions, and to explore if admission status influenced adherence to AR.

METHODS

A Danish descriptive, clinical multi-center study included singleton pregnancies between 22-33 gestational weeks admitted to an antenatal ward or during midwife consultations either prescribed AR due to threatened preterm delivery or uncomplicated controls without restrictions. For seven days participants wore two tri-axial accelerometric SENS® monitors. Accelerometric data included time spent in five different positions, activities, and step counts. At inclusion demographic and obstetric information was collected.

RESULTS

Seventy-two pregnant women participated; 31% were prescribed strict AR, 15% moderate, 3% light, 8% unspecified, and 43% had no AR. Strict AR participants rested in the supine/lateral position for 17.7 median hours/day (range:9.6-24.0); sat upright 4.9 h/day (0.11-11.7); took 1,520steps/day (20-5,482), and 64% were inpatients. Moderate AR participants rested in the supine/lateral position for 15.1 h/day (11.5-21.6); sat upright 5.6 h/day (2.0-9.3); took 3,310steps/day (467-6,968), and 64% were outpatients. Participants with no AR rested 10.5 h/day (6.3-15.4) in supine/lateral position; sat upright 7.6 h/day (0.1-11.4) and took 9,235steps/day (3,225-20,818). Compared to no restrictions, participants with strict or moderate AR spent significant more time in physical resting positions and took significant fewer mean steps. Among strict AR admission status did not alter time spent in the physical positions, nor the step count.

CONCLUSIONS

Overall, participants adhered highly to the recommended AR. However, discriminating between strict and moderate AR recommendations did not alter how physical resting positions and activities were carried out. The admission status did not influence how participants adhered to strict AR.

The association between level of physical activity and pregnancy rate after embryo transfer: a prospective study

RESEARCH QUESTION

Is physical activity after embryo transfer, as assessed by a smart band activity tracker, associated with decreased pregnancy rates?

DESIGN

Prospective observational cohort study comprising infertile women aged < 38 years, who had undergone fewer than three previous embryo transfers, achieved a good ovarian response and were undergoing frozen-thawed embryo transfer in a tertiary-referral centre. A validated smart band activity tracker was used to assess physical activity level immediately after the embryo transfer and until the pregnancy test. No specific recommendations were given to participants on level or intensity of physical activity. Physicians and patients were blinded to the data stored in the pedometer. Primary outcome was ongoing pregnancy rate.

RESULTS

Fifty women met the inclusion criteria. Ongoing pregnancy rate was 30%. In a pooled analysis, participants walked significantly fewer steps per day on the day of embryo transfer compared with the first 2 days after embryo transfer (4075, interquatile range [IQR] 2932-5592 versus 5204, IQR4203-8584, P = 0.01). No significant difference was observed between pregnant women and non-pregnant women in the median steps per day after embryo transfer until serum beta-HCG was measured (7569, IQR 6008-10884 versus 6572.5, IQR 5299-8786, P = 0.43). No significant difference was observed in the median number of steps on the day of embryo transfer or the first 2 days after embryo transfer between pregnant and non-pregnant women.

CONCLUSIONS

A quantitative objective assessment of the association between physical activity and pregnancy rates after frozen-thawed embryo transfer was conducted. Ambulation after embryo transfer has no adverse effect on pregnancy rates and, therefore, women should resume regular activity immediately after embryo transfer.

The cultural construction of preterm birth in the United States

This commentary explores four features of the cultural construction of pregnancy and childbirth in the United States: risk categorization as an aspect of reproductive governance, medicalization, intensive mothering with its implications for gender stratification, and the definition of personhood as beginning at conception. The cultural construction of preterm births (those that end before gestation is complete at about 37 weeks) is interwoven with beliefs about risk in pregnancy. Health risk categories overlap with socially stigmatized characteristics and behaviors, opening sub-groups of women up to intensive surveillance and control. The belief that preterm births are preventable and treatable reinforces medical authority and rationalizes the large allocation of resources to specialty (as opposed to primary) maternal and infant care. Expectations for maternal behavior when preterm birth is threatened and when it occurs reinforce norms of intensive mothering, while the ability to keep preterm infants alive reinforces beliefs about fetal personhood. In these ways, the cultural construction of preterm birth in the U.S. holds the broader construction of pregnancy and childbirth in place by raising the stakes of deviation from norms of reproduction to matters of criminality, death, or serious disability.

Prenatal bed rest in developed and developing regions: a systematic review and meta-analysis

BACKGROUND

Bed rest is prescribed by most maternity health care professionals for high-risk pregnancy complications, but the impact of bed rest at home and in hospital has not been explored. Our aim was to quantify the influence of bed rest on maternal/fetal health outcomes in developed and developing regions.

METHODS

We conducted a systematic review and meta-analysis of randomized controlled trials. We conducted a structured search through MEDLINE, Embase, CINAHL, Web of Science and the Cochrane Library through Mar. 7, 2019. Trials comparing standard care to standard care plus bed rest after 20 weeks' gestation were assessed. Outcomes included infant birth weight, being small for gestational age, gestational age, premature or very premature birth, perinatal death, admission to the neonatal intensive care unit, preterm rupture of membranes, hypertensive disorders of pregnancy, preeclampsia and gestational diabetes mellitus.

RESULTS

We identified 1191 publications, of which 43 were assessed for eligibility. Sixteen publications reporting on 14 unique studies (2608 women, 3328 infants) were included in the analysis. Overall, maternal/newborn outcomes were similar between women on bed rest and those not on bed rest. In subgroup analyses of developed and developing regions, length of gestation was shorter with bed rest (weighted mean difference -0.77 wk, 95% confidence interval [CI] -1.26 to -0.27, I ² = 0%), and the risk of a very premature birth was increased (risk ratio 2.07, 95% CI 1.15 to 3.73, I ² = 0%) in developed countries.

INTERPRETATION

In developed regions, treatment of complicated pregnancies with more than 1 week of bed rest results in worse newborn outcomes. Additional studies are required to determine whether bed rest or hospital admission improves outcomes in developing regions. PROSPERO Trial registration number: CRD42018099237.

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.

The Effect of Activity Restriction on Infant's Birth Weight and Gestational Age at Birth: PRAMS Data Analysis

BACKGROUND:

Activity restriction is extensively prescribed for pregnant women with major comorbidities despite the lack of evidence to support its effectiveness in preventing preterm birth or low birth weight.

PURPOSE:

To determine the moderation effect of home activity restriction for more than a week on infant's birth weight and gestational age at birth for high-risk women with obstetrical and medical comorbidities.

METHODS:

A secondary analysis of 2004-2008 New York Pregnancy Risk Assessment Monitoring System was conducted with 1426 high-risk women.

RESULTS:

High-risk group included 41% of women treated with activity restriction and 59% of those not treated with activity restriction. Women with preterm premature rupture of membrane (PPROM) who were treated with activity restriction had a lower infant birth weight ( b = -202.85, p = ≤.001) and gestational age at birth ( b = -.91, p = ≤.001) than those without activity restriction. However, women with preterm labor and hypertensive disorders of pregnancy who were not treated with activity restriction had lower infant gestational age at birth ( b = -96, p = ≤.01) and ( b = -92, p = ≤.001), respectively, compared to those who were treated with activity restriction.

CONCLUSION:

Findings suggest a contrary effect of activity restriction on infants born to women with PPROM, which is a major reason for prescribing activity restriction. The current study results may trigger the need to conduct randomized control trials to determine the effect of severity of activity restriction on maternal and infant outcomes.

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.