Observational study in an outpatient clinic specializing in treating opioid-dependent pregnant women: neonatal abstinence syndrome in infants exposed to methadone-, buprenorphine- and slow-release oral morphine

Background: The factors determining severity and course of Neonatal Abstinence Syndrome (NAS) in infants born to opioid-dependent pregnant women are still poorly understood. Aim: To compare and evaluate Neonatal Abstinence Syndrome (NAS) in 390 infants born to opioid-dependent women undergoing comprehensive treatment during pregnancy, including methadone (n=184), buprenorphine (n=77) and slow-release oral morphine (SROM, n=129) maintenance therapy. Materials and Methods: An observational design was applied for this complete case analysis, taking into account maternal opioid dose at time of delivery, third trimester concomitant consumption of opioids, benzodiazepines and nicotine, as well as breastfeeding status. Results: The infants exposed to buprenorphine before birth had significantly lower average (p<0.001) and peak NAS scores (p<0.001), needed less morphine for their NAS treatment (p<0.00 I), had shorter mean durations of treatment (p<0.001) and hospital stay (p<0.001) compared with the infants exposed to methadone or SROM. No associations were found between NAS parameters and maternal opioid dose in the buprenorphine group, where concomitant consumption of benzodiazepines and opioids did not influence NAS significantly. Breastfeeding status did not influence NAS in buprenorphine-exposed neonates, in contrast to children in the methadone- or SROM-group. Conclusions: Breastfeeding proved to be especially beneficial to methadone- and SROM-exposed infants whose NAS showed significant, but weak, associations with daily maternal opioid dose. Buprenorphine seems recommendable for women who respond well to it; further research is needed for SROM administration during pregnancy. Cautious interpretation of the results is warranted, because of the individually tailored treatment and subsequent non-random medication group assignment.