Aim: To identify factors that predict the expression of neonatal abstinence syndrome (NAS) in infants exposed to methadone or buprenorphine in utero.
Design and setting: Multi-site randomized clinical trial in which infants were observed for a minimum of 10 days following birth, and assessed for NAS symptoms by trained raters.
Participants: A total of 131 infants born to opioid dependent mothers, 129 of whom were available for NAS assessment.
Measurements: Generalized linear modeling was performed using maternal and infant characteristics to predict: peak NAS score prior to treatment, whether an infant required NAS treatment, length of NAS treatment and total dose of morphine required for treatment of NAS symptoms.
Findings: Of the sample, 53% (68 infants) required treatment for NAS. Lower maternal weight at delivery, later estimated gestational age (EGA), maternal use of selective serotonin re-uptake inhibitors (SSRIs), vaginal delivery and higher infant birthweight predicted higher peak NAS scores. Higher infant birthweight and greater maternal nicotine use at delivery predicted receipt of NAS treatment for infants. Maternal use of SSRIs, higher nicotine use and fewer days of study medication received also predicted total dose of medication required to treat NAS symptoms. No variables predicted length of treatment for NAS.
Conclusions: Maternal weight at delivery, estimated gestational age, infant birthweight, delivery type, maternal nicotine use and days of maternal study medication received and the use of psychotropic medications in pregnancy may play a role in the expression of neonatal abstinence syndrome severity in infants exposed to either methadone or buprenorphine.
Trial registration: ClinicalTrials.gov NCT00271219.
© 2012 The Authors, Addiction © 2012 Society for the Study of Addiction.