Objective To determine whether obstetric and maternal factors relate to faecal incontinence at three months postpartum. Setting Maternity units in Aberdeen (Scotland), Birmingham (England) and Dunedin (New Zealand). Population All women who delivered during one year in the three maternity units. Methods Postal questionnaire at three months postpartum, to obtain information on faecal incontinence, linked to obstetric casenote data. Main outcome measures Prevalence of faecal incontinence. Results 7879 questionnaires were returned, a 71.7% response rate. The prevalence of faecal incontinence was 9.6%. with 4.2% reporting this more often than rarely. Logistic regression, confined to primiparae, showed that forceps delivery was a predictor of an increased risk of symptoms (OR = 1.94, 95% CI 1.30 to 2.89) while vacuum extraction was not associated. Caesarean section was marginally associated with a reduced risk (OR = 0.58, 95% CI 0.35 to 0.97). Older maternal age, Indian sub-continent ethnic origin and body mass index 'not known' also showed significant associations. No associations were found for induced labour, duration of second stage labour, episiotomy, laceration or birthweight. Conclusions Women delivered by forceps had almost twice the risk of developing faecal incontinence, whereas vacuum extraction was not associated with faecal incontinence at three months postpartum. Caesarean section appears to offer some protection.