A prospective study on buprenorphine use during pregnancy: effects on maternal and neonatal outcome.

Background: Exposure to illicit drugs in utero is associated with low birth weight and premature birth. Therefore, maintenance therapy for opioid dependence during pregnancy has been recommended to help withdrawal from street drugs, in order to improve maternal health and decrease risks to the fetus.

Methods: In 2002-2005, 67 pregnancies of 66 buprenorphine users were followed prospectively in an outpatient multidisciplinary antenatal setting by an obstetrician, a midwife, a psychiatric nurse and a social worker. Decreasing doses or even abstinence from buprenorphine was encouraged. Outcome measures were daily buprenorphine dose, fetal growth, gestational age at birth, mode of delivery, birth weight, Apgar scores, umbilical pH values, and occurrence of neonatal abstinence syndrome [NAS]. National statistics were used as reference values.

Results: The daily dose of buprenorphine decreased by 2.3 mg (median, range increase of 8 mg to decrease of 24 mg). There were no more incidences of premature birth, cesarean section, low Apgar scores (< or = 6) or umbilical artery pH <7.05 at birth than in the national register, despite the lower birth weight. A total of 91% of the infants needed treatment in a neonatal care unit, 76% had NAS, and 57% needed morphine replacement therapy. Seven infants were taken into care directly from the maternity hospital. Two sudden infant deaths occurred later.

Conclusions: The pregnancies and deliveries of buprenorphine-using women were uneventful, but severe NAS and need for morphine replacement therapy was seen in 57% of the buprenorphine-exposed newborns. A high number of sudden infant deaths occurred.