Buprenorphine versus methadone in pregnant opioid-dependent women: a prospective multicenter study

In order to investigate the effects of exposure to buprenorphine compared with methadone during pregnancy, a prospective multicenter study was conducted in collaboration with maternity hospitals, maintenance therapy centers, and general practitioners involved in addiction care. Ninety pregnant women exposed to buprenorphine and 45 to metadone were selected for the study.

During pregnancy, some women were exposed to illicit agents: cannabis (42% in the buprenorphine group vs. 58% in the methadone-treated group), heroin (17% vs. 44%), or cocaine (3% vs. 11%). Pregnancies ended in 85 vs. 40 live births, one vs. two stillbirths, two vs. one spontaneous abortion, two vs. one voluntary termination, and one vs. one medical termination in the buprenorphine and the methadone groups, respectively. Newborns had a birth weight of 2,892 ± 506 g (buprenorphine) vs. 2,731 ± 634 g (methadone) and a body length of 47.6 ± 2.5 cm vs. 47.1 ± 3 cm. 18.8% vs. 10% of newborns were delivered before 37 weeks of amenorrhea. Neonatal withdrawal syndrome occurred more frequently in the methadone group (62.5% vs. 41.2, p = 0.03). After adjustment for heroin exposure in late pregnancy, rates of neonatal withdrawal were no longer different between the methadone and buprenorphine groups. Twenty-one babies (84%) in the methadone group and 20 (57%) in the buprenorphine group (p = 0.03) required opiate treatment.

We did not observe more frequent malformations or cases of withdrawal syndrome in the buprenorphine group than in the methadone-treated group. Buprenorphine appears to be as safe as the currently approved substitute methadone considered to date as the reference treatment for pregnant opioid-dependent women.