Safety of Heavy Resistance Exercise During Pregnancy and Postpartum: A Controlled, Prospective Cohort Study

Objective : To address the knowledge gap on the influence of heavy free-weight resistance exercise on the health of the pregnant athlete and infant. Design : This is a prospective, controlled cohort study with two groups of pregnant women; those engaging in mainly heavy free-weight resistance exercise (REX, n = 33) and those regularly physically active (REF, n = 20). Data originate from eight questionnaires answered prospectively throughout pregnancy and 12 months postpartum. Variables cover exercise routines, pregnancy symptoms and complications, fetal growth, delivery, and mother and infant’s health. Results : Bayesian logistic regression with random and fixed effects identified group membership as a significant predictor of proteinuria, with REX having higher exposure (posterior inclusion probability [PIP] = 1.00; β 1 = 197.07, 95% credible interval [CrI] [163.05, 231.08]). Further, Bayesian logistic regression with random and fixed effects confirmed a higher risk of urinary incontinence in the REF group during pregnancy (PIP = 0.98; β 1 = −1.17, 95% CrI [−1.89, −0.46]). Gas incontinence was also found more common in the REF group during pregnancy (PIP = 1.00; β 1 = −7.62, 95% CrI [−8.68, −6.57]) and postpartum (PIP = 0.91; β 1 = −49.39, 95% CrI [−53.57, −45.43]). There were no significant differences in the postpartum period for fecal and urinary incontinence, injuries, infant health outcomes (all PIP < 0.01), or need for assisted delivery (PIP = 0.33). Conclusion : Female athletes experienced in heavy resistance exercise, who continue training during pregnancy and postpartum, do not face increased pregnancy complications. These findings provide evidence supporting safety of such exercise. Yet we highlight the need for a confirmatory study under full clinical supervision.