OBJECTIVE: To compare the duration of labour and the birth outcome in a group of primiparous women who had been raped after the age of 16, with a control group from the same birth cohort. DESIGN: Cohort study. SETTING: University Hospital of North Norway. SAMPLE: Fifty women raped as adults and 150 controls. METHODS: Data about birth outcomes in the first pregnancy were collected from the patient files and data concerning the assault were obtained in a subsequent pregnancy through consultations with the women who had been raped. Birth outcomes in the group of women who had been raped were compared with matched controls using a multivariable logistic regression model. MAIN OUTCOME MEASURES: Caesarean section, operative vaginal delivery and duration of labour. RESULTS: During their first delivery, the women who had been raped had an increased risk for caesarean section (adjusted odds ratio 15.7, 95% CI 5.0-49.1) and for assisted vaginal delivery (adjusted odds ratio 13.1, 95% CI 4.9-34.5) when compared with controls. The group of women who had been raped had a longer second stage of labour than the control group (120 versus 55 minutes, P