Neonatal abstinence syndrome (NAS) has been of increasing concern. Studies suggest that prenatal exposure to buprenorphine may be preferred to methadone in regard to neonatal withdrawal. Our aim was to determine whether the incidence and severity of NAS are different between babies prenatally exposed to methadone or buprenorphine in pregnancy. This retrospective analysis of infants ≥ 35-weeks-old exposed to methadone/buprenorphine alone or in conjunction with other substances in utero. They were divided into four groups: 1-methadone alone (Met), 2-buprenorphine alone (Bup), 3 and 4-those exposed to methadone and buprenorphine, respectively, in conjunction with other drugs (Met+ and Bup+). The frequency of NAS treatment, duration of treatment (LOT) and length of stay (LOS) were compared between groups. Of the 290 mothers, 59% were in the Met group, 18% in the Bup group, 14% in the Met or Bup and another opiate group, and 9% took methadone or buprenorphine plus various other substances. Infants born to Met/Met+ mothers had a four-times higher likelihood of developing NAS (p < 0.001). There was no difference in the LOS (p = 0.08) or LOT (p = 0.11) between groups. The buprenorphine treatment in pregnancy decreased the risk of babies developing NAS. However, once the NAS required pharmacological treatment, the type of maternal prenatal exposure did not affect the LOS or LOT.
Keywords: buprenorphine; length of treatment; methadone; neonatal abstinence syndrome (NAS); opioids; outcomes.