Reproductive history of parous women and urinary incontinence in midlife: A National Birth Cohort follow-up study.

Objective: To investigate how reproductive history was associated with urinary incontinence in midlife.

Design: A follow-up study.

Setting: Denmark.

Population: A total of 39 977 mothers who participated in the Maternal Follow up (2013-2014) in the Danish National Birth Cohort. National registries provided their reproductive history.

Methods: How parity, mode of birth and obstetric tears associated with urinary incontinence were estimated with adjusted odds ratios (OR) and 95% CI using logistic regression.

Main Outcome Measures: Self-reported urinary incontinence including subtypes stress, urge and mixed urinary incontinence.

Results: At an average age of 44 years, the prevalence of any urinary incontinence was 32% (21% stress, 2% urge, and 8% mixed urinary incontinence). Women with two births more often had urinary incontinence than women with one birth (OR 1.20, 95% CI 1.10-1.31). Compared with women with only spontaneous births, a history of only caesarean sections was associated with much lower odds of urinary incontinence (OR 0.39, 95% CI 0.35-0.42) and a history of instrumental births with slightly lower odds (OR 0.92, 95% CI 0.86-0.98). Compared with no tear/first-degree tear as the largest tear, episiotomy was associated with less urinary incontinence (OR 0.91, 95% CI 0.86-0.97) whereas third/fourth-degree tears were associated with more (OR 1.14, 95% CI 1.04-1.25). Findings were mainly explained by similar associations with stress and mixed urinary incontinence.

Conclusions: Vaginal birth was associated with a higher risk of long-term urinary incontinence, but our results indicate that this risk may be reduced by shortening the second stage of birth.