Outcomes Associated With Illicit Fentanyl Exposure During Pregnancy: A Retrospective Cohort Study

BACKGROUND: Illicitly manufactured fentanyl (IMF) is the predominant opioid in the US drug supply and is a major contributor to morbidity and mortality during pregnancy. While prenatal opioid exposure is an established risk factor for neonatal opioid withdrawal syndrome (NOWS), the differential effects of IMF vs other opioids on outcomes are largely unknown. Therefore, we aimed to evaluate the associations between prenatal IMF exposure and fetal, perinatal, and neonatal health outcomes. METHODS: We conducted a retrospective cohort study of pregnant women with opioid use disorder (OUD) and their infants who were born between January 2024 and December 2024. Maternal and infant participants were stratified into 2 groups based on the opioids, IMF vs medications for OUD (MOUDs), identified on urine drug testing at delivery. Descriptive statistics were used to describe the characteristics of cohort participants, while χ2 and t tests were used to evaluate for differences in outcomes between the groups. RESULTS: Among 125 infants, 34 were categorized as IMF exposed, and 91 were categorized as MOUD exposed. Fetal growth restriction, preterm birth, and abnormal growth parameters, including low birth weight and very low birth weight, were more frequently identified among IMF- vs MOUD-exposed infants. In addition, IMF-exposed infants were significantly more likely to require neonatal intensive care unit admission, have a longer neonatal hospital length of stay, and require pharmacologic treatment for NOWS. CONCLUSIONS: Prenatal IMF exposure was associated with significant neonatal morbidity compared with MOUD exposure, highlighting the importance of engagement in maternal substance use treatment during pregnancy to both maternal and neonatal health outcomes.