The association between the interdelivery interval and early postpartum urinary incontinence in women who had consecutive vaginal deliveries: a retrospective cohort study.

Background: Urinary incontinence (UI) is associated with obstetric-related factors; however, the association between the timing of deliveries and UI remains unclear. We examined the association between the interdelivery interval (IDI) and early postpartum UI.

Methods: This retrospective cohort study included 2,492 parous women who had consecutive singleton, full-term, and vaginal deliveries. UI was self-reported by the participants from 42 to 60 days postpartum and was classified using the International Consultation on Incontinence Questionnaire-Urinary Incontinence-Short Form. The IDI was measured as the number of months between 2 consecutive live births, and the participants were divided into 4 groups based on the IDI quartiles. The associations between the IDI and early postpartum UI were assessed using multiple logistic regression models.

Results: The median [interquartile range] IDI for the entire cohort was 62 [40-90] months at the baseline. In general, the restricted cubic splines showed a U-shaped curve association between the IDI and the incidence of early postpartum UI. After fully adjusting for potential confounders, a longer IDI was associated with a lower adjusted odds ratio (aOR) of postpartum UI. Among the 4 groups, the Quartile 3 IDI group had the lowest aOR [aORQuartile 1-Quartile 2: 0.48 (95% CI: 0.36-0.63); aORQuartile 1-Quartile 3: 0.37 (95% CI: 0.27-0.49); aORQuartile 1-Quartile 4: 0.40 (95% CI: 0.28-0.57); the P value for the trend was <0.001). The association between the IDI and UI was more pronounced in the younger women (<35 years old) and the women with a pre-pregnancy body mass index of <25 kg/m (the P values for both interactions were <0.01).

Conclusions: We found that the IDI was independently associated with the incidence of early postpartum UI in parous women. IDI ≥41 months was associated with a lower risk of postpartum UI compared to IDI <41 months.