Aerobic exercise for 35-90 minutes 3-4 times per week during pregnancy can be safely performed by normal-weight women with singleton, uncomplicated gestations because this is not associated with an increased risk of preterm birth or with a reduction in mean gestational age at delivery. Exercise was associated with a significantly higher incidence of vaginal delivery and a significantly lower incidence of cesarean delivery, with a significantly lower incidence of gestational diabetes mellitus and hypertensive disorders and therefore should be encouraged.

Introduction. Gestational hypertensive disorders, including gestational hypertension and preeclampsia, are one of the leading causes of maternal morbidity and mortality. The aim of our study was to evaluate the effect of exercise during pregnancy on the risk of gestational hypertensive disorders. Material and methods. Electronic databases were searched from their inception to February 2017. Selection criteria included only randomized controlled trials of uncomplicated pregnant women assigned before 23 weeks to an aerobic exercise regimen or not. The summary measures were reported as relative risk with 95% confidence intervals. The primary outcome was the incidence of gestational hypertensive disorders, defined as either gestational hypertension or preeclampsia. Results. Seventeen trials, including 5075 pregnant women, were analyzed. Of them, seven contributed data to quantitative meta-analysis for the primary outcome. Women who were randomized in early pregnancy to aerobic exercise for about 30-60 min two to seven times per week had a significant lower incidence of gestational hypertensive disorders (5.9% vs. 8.5%; relative risk 0.70, 95% confidence interval 0.53-0.83; seven studies, 2517 participants), specifically a lower incidence of gestational hypertension (2.5% vs. 4.6%; relative risk 0.54, 95% confidence interval 0.40-0.74; 16 studies, 4641 participants) compared with controls. The incidence of preeclampsia (2.3% vs. 2.8%; relative risk 0.79, 95% confidence interval 0.45-1.38; six studies, 2230 participants) was similar in both groups. The incidence of cesarean delivery was decreased by 16% in the exercise group. Conclusions. Aerobic exercise for about 30-60 min two to seven times per week during pregnancy, as compared with being more sedentary, is associated with a significantly reduced risk of gestational hypertensive disorders overall, gestational hypertension, and cesarean delivery.

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.

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