Effects of prolonged second stage, method of birth, timing of caesarean section and other obstetric risk factors on postnatal urinary incontinence: an Australian nulliparous cohort study.

OBJECTIVE: To investigate the contribution of prolonged labour, method of birth, timing of caesarean section and other obstetric risk factors to postpartum urinary incontinence.
DESIGN: Prospective pregnancy cohort.
SETTING: Six metropolitan public hospitals in Victoria, Australia. SAMPLE: A total of 1507 nulliparous women recruited to the maternal health study in early pregnancy (≤24 weeks).
METHOD: Data from hospital medical records and self-administered questionnaires/telephone interviews at ≤24 and 30-32 weeks of gestation and 3 months postpartum analysed using univariable and multivariable logistic regression. MAIN OUTCOME MEASURE: Urinary incontinence 3 months postpartum in women continent before the index pregnancy.
RESULTS: Of the women continent before pregnancy, 26% reported new incontinence at 3 months postpartum. Compared with women who had a spontaneous vaginal birth, women who had a caesarean section before labour (adjusted odds ratio [OR] 0.2, 95% CI 0.1-0.5) or in the first stage of labour (adjusted OR 0.2, 95% CI 0.1-0.4) were less likely to be incontinent 3 months postpartum. Adjusted OR for incontinence after caesarean section in the second stage of labour compared with spontaneous vaginal birth was 0.5 (95% CI 0.2-1.0). Prolonged second stage labour was associated with increased likelihood of postpartum incontinence in women who had a spontaneous vaginal birth (adjusted OR 1.9, 95% CI 1.1-3.4) or operative vaginal birth (adjusted OR 1.7, 95% CI 1.0-2.8).
CONCLUSIONS: In addition to pregnancy itself, physiological changes associated with the second stage of labour appear to play a role in postpartum urinary incontinence.