Is there an association between the length of the second stage of labour and urinary incontinence in multiparous women?

Objectives: It is unclear whether the length of the second stage of labour plays a role in the development of urinary incontinence (UI). This study aimed to investigate the association between the cumulative length of the second stage of labour in multiparous women and UI. Methods: This was a longitudinal cohort study of women who had undergone three vaginal deliveries (VDs) between 2008 and 2017. UI was assessed using the Urinary Distress Inventory (UDI-6) questionnaire. Women with a cumulative length of the second stage of labour for three deliveries in the upper 90th percentile (study group) were compared with women with a cumulative length of the second stage of labour below the 90th percentile (control group). A sample size of 280 women was needed to detect a 15-point difference in the UDI-6 score between the groups. Results: Thirty-one women were included in the study group and 275 women were included in the control group. Demographic and obstetric characteristics were similar in both groups. There was no between-group difference in mean UDI-6 score: 12.3 +/- 17.5 in the study group and 14.9 +/- 18.2 in the control group (p = 0.55). No association was found between the cumulative length of the second stage of labour and the UDI score. A linear regression model revealed that maternal body mass index was independently associated with UDI-6 score (correlation coefficient 0.67, 95% confidence interval 0.19-1.15; p = 0.006). Conclusion: The cumulative length of the second stage of labour in multiparous women is not associated with UI.