Exercise during pregnancy is associated with a shorter duration of labor. A randomized clinical trial.

Objective: to examine the influence of an exercise program throughout pregnancy on the duration of labor in healthy pregnant women.

Study Design: A randomized clinical trial was used (Identifier: NCT02109588). In all, 508 healthy pregnant women were randomly assigned between 9 and 11 weeks of gestation to either a Control Group (CG, N = 253) or an Exercise Group (EG, N = 255). A moderate aerobic exercise program throughout pregnancy (three weekly sessions) was used as the intervention. Mann-Whitney and Pearson χ tests were performed to analyze differences between groups. Survival techniques through the Kaplan-Meier method were used to estimate the median time to delivery of each group; and Gehan-Breslow-Wilcoxon tests were performed to compare survival distribution between the two arms. The primary outcome studied was the length of the stages of labor. Secondary outcomes included mode of delivery, gestational age, maternal weight gain, preterm delivery, use of epidural, birthweight, Apgar scores and arterial cord pH.

Results: Women randomized to the EG had shorter first stage of labor (409 vs 462 min, p = 0.01), total duration of labor (450 vs 507 min, p = 0.01) as well as combined duration of first and second stages of labor (442 vs 499 min, p = 0.01). The probabilities of a woman being delivered at 250 min and 500 min (median times) were 19.1% and 62.5% in the experimental group vs 13.7% and 50.8% in the control group (Z = -2.37, p = 0.018). Results also revealed that women in the intervention group were less likely to use an epidural; and that the prevalence of neonate macrosomia was higher in the control group.

Conclusion: A supervised physical exercise program throughout pregnancy decreased the duration of the first phase of labor as well as total time of the first two phases together, leading to a decrease in total labor time.