The onset, recurrence and associated obstetric risk factors for urinary incontinence in the first 18 months after a first birth: an Australian nulliparous cohort study.

OBJECTIVE: To investigate the contribution of obstetric risk factors to persistent urinary incontinence (UI) between 4 and 18 months postpartum.
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 of gestation).
METHODS: Data from hospital records and self-administered questionnaires/telephone interviews at ≤24 and 30-32 weeks of gestation and at 3, 6, 9, 12 and 18 months postpartum analysed using logistic regression. MAIN OUTCOME MEASURES: Persistent UI 4-18 months postpartum in women continent before pregnancy.
RESULTS: Of the women who were continent before pregnancy, 44% reported UI 4-18 months postpartum, and 25% reported persistent UI (symptoms at multiple follow ups). Compared with spontaneous vaginal birth, women who had a caesarean before labour (adjusted odds ratio [aOR] 0.4, 95% confidence interval [95% CI] 0.2-0.9), in first-stage labour (aOR 0.4, 95% CI 0.2-0.6) or in second-stage labour (aOR 0.4, 95% CI 0.2-1.0) were less likely to report persistent UI 4-18 months postpartum. Prolonged second-stage labour in women who had an operative vaginal birth was associated with increased likelihood of UI (aOR 2.5, 95% CI 1.3-4.6). Compared with women who were continent in pregnancy, women reporting UI in pregnancy had a seven-fold increase in odds of persistent UI (aOR 7.4, 95% CI 5.1-10.7).
CONCLUSIONS: Persistent UI is common after childbirth and is more likely following prolonged labour in combination with operative vaginal birth. The majority of women reporting persistent UI at 4-18 months postpartum also experienced symptoms in pregnancy.