Maternal Opioid Use Disorder and the Risk of Postneonatal Infant Mortality

Abstract

The risk of serious long-term outcomes for infants born to individuals with opioid use disorder (OUD) is not fully characterized, nor is it well understood whether risks are modified by infant diagnosis of neonatal opioid withdrawal syndrome (NOWS). To characterize the risk of postneonatal infant mortality among infants with a NOWS diagnosis or born to individuals with OUD. The study team conducted a retrospective cohort study of 390 075 infants born from 2007 through 2018 to mothers who were enrolled in Tennessee Medicaid from 183 days prior to delivery through 28 days post partum (baseline). Maternal and infant baseline characteristics were measured using administrative claims and birth certificates, and infants were followed up from day 29 post partum through day 365 or death. Deaths were identified using linked death certificates through 2019. These data were analyzed from February 10, 2022, through March 3, 2023. Infant exposures included birth to an individual with OUD or postnatal diagnosis of NOWS. The study team defined a pregnant individual's OUD status (maternal OUD) as having OUD diagnosis or a maintenance medication prescription fill during baseline; this study defined NOWS as having NOWS diagnosis up to day 28. Groups were categorized by exposures as maternal OUD with NOWS (OUD positive/NOWS positive), maternal OUD without NOWS (OUD positive/NOWS negative), no documented maternal OUD with NOWS (OUD negative/NOWS positive), and no documented maternal OUD or NOWS (OUD negative/NOWS negative, unexposed). The outcome was postneonatal infant death, confirmed by death certificates. Cox proportional hazards models were used, adjusting for baseline maternal and infant characteristics, to estimate adjusted hazard ratios (aHRs) and 95% CIs for the association between maternal OUD or NOWS diagnosis with postneonatal death. Pregnant individuals in the cohort had a mean (SD) age of 24.5 (5.2) years; 51% of infants were male. The study team observed 1317 postneonatal infant deaths and incidence rates of 3.47 (OUD negative/NOWS negative, 375 718), 8.41 (OUD positive/NOWS positive, 4922); 8.95 (OUD positive/NOWS negative, 7196), and 9.25 (OUD negative/NOWS positive, 2239) per 1000 person-years. After adjustment, the risk of postneonatal death was elevated for all groups, relative to the unexposed: OUD positive/NOWS positive (aHR, 1.54; 95% CI, 1.07-2.21), OUD positive/NOWS negative (aHR, 1.62; 95% CI, 1.21-2.17), and OUD negative/NOWS positive (aHR, 1.64; 95% CI, 1.02-2.65). Infants born to individuals with OUD or with a NOWS diagnosis had an increased risk of postneonatal infant mortality. Future work is necessary to create and evaluate supportive interventions for individuals with OUD during and after pregnancy to reduce adverse outcomes.