Exercise throughout pregnancy does not cause preterm delivery: a randomized, controlled trial.

Background: In spite of an extensive knowledge of the physiologic features of exercise during pregnancy, we still lack a comprehensive understanding of the effects of different types, intensities and duration of exercise throughout pregnancy on maternal and fetal well being. The aim of the current study was to examine the influence of an aerobic exercise program throughout pregnancy on gestational age at the moment of delivery.

Methods: This study was a randomized controlled trial. Three hundred and twenty Caucasian (Spanish) healthy pregnant women with singleton gestation were randomly assigned to either an exercise (n = 160) or a control (n = 160) group. Gestational age (weeks) and other outcomes were measured. The exercise program included 85 sessions (general fitness class, 3 times/week, 55-60 min/session from weeks 8-10 to weeks 38-39 of pregnancy).

Results: Two hundred and ninety women were analyzed (exercise group EG, n = 138, control group CG, n = 152). The mean gestational age did not differ between groups (EG= 39.7 ± 1.3 vs CG= 39.6 ± 1.1 weeks, P = .81). Relative to preterm deliveries in EG we found 6 (4.3%) and 11 (7.2%) in CG, (P = .73).

Conclusions: A supervised program of moderate exercise performed throughout pregnancy is not a risk of preterm delivery for healthy pregnant women.