• Caesarean section;
  • cohort study;
  • postpartum;
  • primiparity;
  • urinary incontinence;
  • vaginal birth

Objective  The objectives of this study were to investigate prevalence of urinary incontinence at 6 months postpartum and to study how continence status during pregnancy and mode of delivery influence urinary incontinence at 6 months postpartum in primiparous women.

Design  Cohort study.

Setting  Pregnant women attending routine ultrasound examination were recruited to the Norwegian Mother and Child Cohort Study (MoBa).

Population  A total of 12 679 primigravidas who were continent before pregnancy.

Methods  Data are from MoBa, conducted by the Norwegian Institute of Public Health. Data are based on questionnaires answered at week 15 and 30 of pregnancy and 6 months postpartum.

Main outcome measures  Urinary incontinence 6 months postpartum is presented as proportions, odds ratios and relative risks (RRs).

Results  Urinary incontinence was reported by 31% of the women 6 months after delivery. Compared with women who were continent during pregnancy, incontinence was more prevalent 6 months after delivery among women who experienced incontinence during pregnancy (adjusted RR 2.3, 95% CI 2.2–2.4). Adjusted RR for incontinence after spontaneous vaginal delivery compared with elective caesarean section was 3.2 (95% CI 2.2–4.7) among women who were continent and 2.9 (95% CI 2.3–3.4) among women who were incontinent in pregnancy.

Conclusion  Urinary incontinence was prevalent 6 months postpartum. The association between incontinence postpartum and mode of delivery was not substantially influenced by incontinence status in pregnancy. Prediction of a group with high risk of incontinence according to mode of delivery cannot be based on continence status in pregnancy.