Examination of the association of physical activity during pregnancy after cesarean delivery and vaginal birth among Chinese women

Background: The goal was to study whether higher physical activity can increase the success rate of Vaginal Birth after Cesarean Delivery (VBAC). Methods: We enrolled 823 patients with previous cesarean section delivery history (between January 2015 and December 2017) and measured their physical activity during pregnancy. A final number of 519 patients were included for the trial of labor after cesarean delivery (TOLAC). All patients signed informed consent forms. Results: We conducted bivariate analyses and identified that several variables were associated with successful VBAC: Prior history of vaginal birth (odds ratio [OR] 2.4, 95% CI 1.8-3.9); previous indication for primary cesarean delivery (OR 2.2, 95% CI 1.5-3.0); age younger than 40 years (OR 2.1, 95% CI 1.3-3.4); Weight gain less than 20 kg (OR 1.5, 95% CI 1.3-2.4); high pelvic/birth weight score (OR 1.4, 95% CI 1.1-2.0); no induction of labor (OR 1.9, 95% CI 1.4-2.8); and estimated prenatal fetal weight (OR 1.4, 95% CI 1.2-1.5). We also found that the bivariate association between physical activity and VBAC was significant (p = 0.002). In addition, there was higher odds of VBAC in women who had active physical activity of more than 150 min/week (adjusted OR 1.86, 95% CI 1.69-2.07). Lower odds of VBAC was associated with older age, weight gain during pregnancy, induction of labor, and having estimated prenatal fetal weight more than 3500 g. Conclusion: Physical activity during pregnancy may influence the success rate of VBAC in Chinese women. Future studies will be needed to prove the robustness of this association using more detailed exposure and outcome definitions.