Objective: Infants with neonatal abstinence syndrome have significant morbidity, but the association with birth defects is poorly understood. This study aimed to determine how neonatal abstinence syndrome is related to birth defects, including the joint impact of neonatal abstinence syndrome and birth defects on infant morbidity.
Method: A population-based cohort of 1,944,804 neonates born in the hospitals of Quebec, Canada (1989-2013), was compiled with data on maternal exposures and infant outcomes after delivery. The prevalence of neonatal abstinence syndrome and birth defects was estimated, including the association with neonatal morbidity and mortality after adjustment for maternal age, parity, morbidity, socioeconomic deprivation, and time period. Joint effects of neonatal abstinence syndrome and birth defects on infant outcomes were assessed.
Results: Infants with neonatal abtinence syndrome had a higher prevalence of birth defects (705.7 per 10,000) than infants with no drug exposure (568.9 per 10,000). Compared with no exposure, infants with neonatal abstinence syndrome had 1.35 times the chance of having birth defects (95% confidence interval [1.14, 1.59]). Associations were strongest for central nervous system defects (risk ratio = 6.06, 95% confidence interval [3.93, 9.35]). Neonatal abstinence syndrome combined with birth defects was associated with significantly more infant morbidity and mortality.
Conclusions: Infants with neonatal abstinence syndrome have a greater prevalence of birth defects, particularly defects of the central nervous system. Neonatal abstinence syndrome with birth defects may be an underappreciated contributor to infant morbidity.