AIMS: To investigate the impact of the first pregnancy and delivery on the prevalence and types of urinary incontinence during pregnancy and 1 year after delivery. METHODS: The study was a prospective cohort study with a control group. Primiparous women, who delivered in our department from June 2003 to July 2005, participated. The women filled out a questionnaire 2-3 days after the delivery and a new questionnaire after 1 year. The questionnaires comprised basic characteristics and symptoms of urinary incontinence. An attempted age-matched control group of nulliparous women was included, and filled out similar questionnaires. Prevalences and types of urinary incontinence, and a combined severity- and bother-score (ICIQ-SF score) among the incontinent women, were calculated and compared. RESULTS: The two groups differed significantly in age and most basic characteristics. During pregnancy, the prevalence of any type of urinary incontinence in the primiparous group was 32.1%, compared to 13.8% in the control group. Adjusted OR = 3.3 (95%CI = 2.4-4.4). One year after delivery, the prevalence in the primiparous group was 29.3%, compared to 16.6% in the control group. Adjusted OR = 2.5 (95%CI = 1.8-3.5). ICIQ-SF mean scores among the incontinent women varied insignificantly between 5.8 and 6.2. CONCLUSIONS: The prevalence of urinary incontinence during pregnancy was 3.3 times higher compared with a control group of nulliparous women. After 1 year, the difference was reduced, but still 2.5 times higher in the primiparous group. The symptoms and impact on quality of life seemed to be mild to moderate in both groups. Neurourol. Urodynam. © 2011 Wiley Periodicals, Inc.