Aim: To compare the effects of fetal buprenorphine and methadone exposure during maintenance treatment of pregnant heroin dependent subjects.
Design and setting: A population based comparison of consecutive, prospectively followed buprenorphine-exposed pregnancies in Stockholm County, Sweden, to retrospectively analyzed consecutive methadone-exposed pregnancies.
Participants: All 47 pregnancies in 39 women with opiate dependence and buprenorphine maintenance treatment 2001-2006, and all 35 methadone-exposed pregnancies (26 women) 1982-2006 in Stockholm County.
Measurements: Intrauterine growth, birth outcome, malformations, neonatal adaptation, withdrawal syndrome and infant mortality.
Findings: Buprenorphine-exposed pregnancies resulted in 47 uneventful live births (2 twin pairs), 1 stillbirth (for which no explanation was found) and 1 miscarriage. The birth weight of the infants was normal. Neonatal abstinence syndrome (NAS) occurred in 19 cases (40.4%), the majority mild in nature and only 7 (14.9%) needing withdrawal treatment. Compared to 35 infants born after intrauterine methadone exposure at the same hospital since 1982 (77.8% of them exhibiting NAS and 52.8% needing withdrawal treatment), there were significant advantages with buprenorphine treatment: birth weight was higher, due to longer gestation. Incidence of NAS of any intensity, as well as incidence of NAS that required pharmacological treatment was lower, while length of hospital stay was shorter. When buprenorphine treatment started pre-conception, NAS at any level was significantly less frequent than in subjects with post-conception initiated treatment (7/27, 26%; 12/20, 60%, respectively).
Conclusions: Data from this non-randomized comparison suggest that buprenorphine may offer advantages for treatment of opiate dependence during pregnancy.