Despite the widespread avoidance of detoxification in the second or third trimesters, there is no clear evidence to support the view that methadone withdrawal is harmful in pregnant opiate dependent women. We investigated the safety of methadone detoxification in pregnancy in a retrospective case series of 101 pregnant opiate dependent women who underwent a 21-day in-patient methadone withdrawal. One miscarriage occurred in the first trimester (n = 5; incidence rate ratio of 6.87 compared to population norms (95% CI = 0.16-47.3; p =.15)). No miscarriages were observed in the second trimester (n = 54; incidence rate ratio = 0 compared to population norms (95% CI = 0-3.69; p =.27). One premature delivery occurred in the third trimester (1 in 158 weeks at risk compared to 1 in 150 weeks in population norms; p =.16). Methadone detoxification treatment was not associated with any increased risk of miscarriage in the second trimester or premature delivery in the third trimester.