Association of medication-assisted treatment and short acting opioids with newborn head circumference and birth weight

OBJECTIVE: We compared the association of methadone, buprenorphine, and short-acting opioid exposure with newborn head circumference (HC) and birth weight (BW), and evaluated gestational age (GA) as a mediator. STUDY DESIGN: We included newborns born 2013-2018 identified by neonatal abstinence syndrome diagnosis code (N = 572) and birthday-matched unexposed controls (N = 571). Linear regressions of opioid exposure with HC and BW controlled for tobacco, marijuana, cocaine, gabapentin, cesarean section, Medicaid, and newborn sex, with mediation analysis by GA. RESULT: Methadone was associated with 0.81 cm lower HC (95% CI = -1.22, -0.40) and 0.23 kg lower BW (95% CI = -0.35, -0.10) with approximately 24% and 41% mediated by GA, respectively. Buprenorphine and short acting opioids were not associated with HC or BW. CONCLUSION: Methadone exposed newborns have smaller HC and lower BW not fully attributable to younger GA, suggesting a direct effect of methadone on intrauterine growth. Exploration of potential developmental consequences of this is urgently needed