Exercise during pregnancy and risk of preterm birth in overweight and obese women: a systematic review and meta‐analysis of randomized controlled trials

Abstract

Introduction. The incidence of overweight and obesity in pregnancy has risen significantly in the last decades. Overweight and obesity have been shown to increase the risk for some adverse obstetric outcomes. Lifestyle interventions, such as diet, physical activity and behavior changes, may reduce these risks by promoting weight loss and/or preventing excessive weight gain. The possible impact of exercise on the risk of preterm birth (PTB) in overweight or obese women is controversial. Therefore, the aim of our study was to evaluate the effect of exercise on the risk of PTB in overweight or obese pregnant women. Material and methods. MEDLINE, EMBASE, Web of Sciences, Scopus, ClinicalTrial.gov, OVID and Cochrane Library were searched from their inception to November 2016. This meta-analysis included only randomized controlled trials (RCTs) of pregnant women assigned or not assigned before 25 weeks to an aerobic exercise regimen. Types of participants included overweight or obese (mean body mass index ≥25 kg/m 2 ) women with singleton pregnancies without any contraindication to physical activity. The summary measures were reported as relative risk (RR) or as mean difference (MD) with 95% confidence intervals (CI). The primary outcome was the incidence of PTB <37 weeks. Results. Nine trials including 1502 overweight or obese singleton gestations were analyzed. Overweight and obese women who were randomized in early pregnancy to aerobic exercise for about 30-60 min three to seven times per week had a lower percentage of PTB <37 weeks (RR 0.62, 95% CI 0.41-0.95) compared with controls. The incidence of gestational age at delivery (MD 0.09 week, 95% CI À0.18 to 0.24) and cesarean delivery (RR 0.93, 95% CI 0.77-1.10) were similar in both groups. Women in the exercise group had a lower incidence of gestational diabetes mellitus (RR 0.61, 95% CI 0.41-0.90) compared with controls. No differences in birthweight (MD 16.91 g, 95% CI À89.33 to 123.19), low birthweight (RR 0.58, 95% CI 0.25-1.34), macrosomia (RR 0.92,) and stillbirth (RR 2.13, between the exercise group and controls were found. Conclusions. Overweight and obese women with singleton pregnancy can be counseled that, compared with being more sedentary, aerobic exercise for about 30-60 min three to seven times per week during pregnancy is associated with a reduction in the incidence of PTB. Aerobic exercise in overweight and obese pregnant women is also associated with a significant prevention of gestational diabetes mellitus, and should therefore be encouraged.

Metformin reduces maternal weight gain in obese pregnant women: A systematic review and meta‐analysis of two randomized controlled trials

“…As demonstrated in previous studies that investigated other interventions aimed at reducing BW in obese pregnant women, including diet and lifestyle interventions, we showed no significant effect for this outcome.…”

“…This meta-analysis of two RCTs including 849 obese pregnant women showed that the use of metformin in this population was associated with a significant reduction in MWG. Metformin was also associated with a significantly lower incidence of PE and admission to the NICU, while no differences were found with the As demonstrated in previous studies that investigated other interventions aimed at reducing BW in obese pregnant women, including diet and lifestyle interventions, [23][24][25][26] we showed no significant effect for this outcome.…”

Exercise during pregnancy and risk of gestational hypertensive disorders: a systematic review and meta‐analysis

“…Di Mascio et al in a recent meta‐analysis of nine studies including 2059 women, showed that in low‐risk uncomplicated normal‐weight singleton gestations, aerobic exercise can be safely performed, as this is not associated with an increased risk of preterm birth or with a reduction in mean gestational age at delivery but is associated with higher chance of vaginal delivery and lower rate of cesarean delivery as well as a lower incidence of gestational diabetes mellitus . Another meta‐analysis by Magro‐Malosso et al found that overweight or obese women with singleton pregnancy who were randomized to 30–60 min three to seven times per week during pregnancy had a reduced risk of preterm birth.…”

Very tight vs. tight control: what should be the criteria for pharmacologic therapy dose adjustment in diabetes in pregnancy? Evidence from randomized controlled trials

“…Trials in women treated only with exercise or diet at the time of randomization were excluded. Exercise in pregnancy has been shown to reduce the risk of diabetes in both normal‐weight and overweight and obese women , as well as to improve pregnancy outcome in those with GDM .…”