VAGINAL delivery increases the likelihood of stress and mixed urinary incontinence in women, with risk patterns differing before and after natural menopause. This is according to a large cross-sectional study of U.S. women.
Researchers analyzed data from the National Health and Nutrition Examination Survey (NHANES) spanning 2007 to 2018 to investigate the cumulative impact of the number of vaginal deliveries on urinary incontinence subtypes, including stress urinary incontinence (SUI), urge urinary incontinence (UUI), and mixed urinary incontinence (MUI). A total of 4,046 premenopausal and 2,698 postmenopausal women were included in the analysis, which used multivariable logistic regression, restricted cubic spline modeling, and subgroup interaction testing.
Among premenopausal women, one or more vaginal deliveries significantly raised the risk of SUI compared with nulliparity. Odds ratios were 2.53 for one delivery, 3.73 for two deliveries, and 2.94 for three or more deliveries (all P<0.001). In postmenopausal women, the association was present but attenuated, with elevated SUI risk seen only with two or more vaginal deliveries (OR=1.52 for two; OR=1.62 for three or more, all P<0.05). For MUI, two vaginal deliveries increased risk in both premenopausal (OR=1.78, P=0.012) and postmenopausal women (OR=1.57, P=0.049). No significant associations were identified between number of deliveries and UUI in either group. Nonlinear modeling revealed an inverse U-shaped relationship between number of deliveries and SUI risk, and an L-shaped relationship with MUI, suggesting that risk does not increase indefinitely with higher delivery counts. The findings underscore the role of vaginal delivery in shaping lifetime urinary incontinence risk, with natural menopause exerting a modifying effect that reduces, but does not eliminate, the impact. The authors conclude that while stress and mixed urinary incontinence remain strongly associated with parity, additional research, particularly longitudinal studies, is needed to confirm and clarify these relationships. Reference: Bai X et al. Associations between the number of vaginal delivery and urinary incontinence in women before and after natural menopause: a cross-sectional study. Int J Womens Health. 2025;17:3315-3330.
