To assess the association between fear of childbirth and duration of labour. A prospective study of women from 32 weeks of gestation through to delivery. Akershus University Hospital, Norway. A total of 2206 pregnant women with a singleton pregnancy and intended vaginal delivery during the period 2008-10. Fear of childbirth was assessed by the Wijma Delivery Expectancy Questionnaire (W-DEQ) version A at 32 weeks of gestation, and defined as a W-DEQ sum score ≥ 85. Information on labour duration, use of epidural analgesia and mode of delivery was obtained from the maternal ward electronic birth records. Labour duration in hours: from 3-4 cm cervical dilatation and three uterine contractions per 10 minutes lasting ≥ 1 minute, until delivery of the child. Fear of childbirth (W-DEQ sum score ≥ 85) was present in 7.5% (165) of women. Labour duration was significantly longer in women with fear of childbirth compared with women with no such fear using a linear regression model (crude unstandardized coefficient 1.54; 95% confidence interval 0.87-2.22, corresponding to a difference of 1 hour and 32 minutes). After adjustment for parity, counselling for pregnancy concern, epidural analgesia, labour induction, labour augmentation, emergency caesarean delivery, instrumental vaginal delivery, offspring birthweight and maternal age, the difference attenuated, but remained statistically significant (adjusted unstandardized coefficient 0.78; 95% confidence interval 0.20-1.35, corresponding to a 47-minute difference). Duration of labour was longer in women with fear of childbirth than in women without fear of childbirth.