Urinary incontinence: prevalence and risk factors at 16 weeks of gestation

Objective To evaluate the prevalence of urinary incontinence at 16 weeks of gestation and to identify possible maternal and obstetric risk factors. Design Cross-sectional study and cohort study. Setting Department of Obstetrics and Gynaecology, Aarhus University Hospital, Denmark. Population Cross-sectional study: 7795 women attending antenatal care. Cohort study: a sub-group of 1781 pregnant women with one previous delivery at our department. Results Prevalence and maternal risk factors: the prevalence of urinary incontinence within the preceding year was 8.9% among women at 16 weeks of gestation (nulliparae, 3.9%, para 1, 13.8%, para 2+, 16.2%). Stress or mixed incontinence occurred at least weekly in 3% of all the women. After adjusting for age, parity, body mass index, smoking, previous abortions, and previous lower abdominal or urological surgery in a logistic regression model, primiparous women who had delivered vaginally had higher risk of stress or mixed urinary incontinence than nulliparous women (OR 5.7; 95% CI 3.9-8.3). Subsequent vaginal deliveries did not increase the risk significantly. Young age, body mass index > 30, and smoking were possible risk factors for developing urinary incontinence. Obstetric factors: weight of the newborn > 4000 g (OR 1.9; 95% CI 1.0-3.6) increased the risk of urinary incontinence; mediolateral episiotomy in combination with birthweight > 4000 g also increased the risk (OR 3.5; 95% CI 1.2-10.2); a number of other intrapartum factors did not increase the risk of urinary incontinence. Conclusions The first vaginal delivery was a major risk factor for developing urinary incontinence; subsequent vaginal deliveries did not increase the risk significantly. Birthweight > 4000 g increased the risk; episiotomy in combination with birthweight > 4000 g also increased the risk.