Effects of Xylazine Exposure on Maternal, Perinatal and Infant outcomes - ABSTRACT Overdose deaths among pregnant persons who use drugs (PPWUD) account for 1 in 6 pregnancy-associated deaths in the United States. An escalating maternal death rate is largely due to the use of high-potency synthetic opioids, like illicitly manufactured fentanyl (IMF) and xylazine has been increasingly identified as an IMF adulterant. Xylazine exposure has been linked to multiple complications such as severe necrotic wounds and profound sedation but the additional risks of exposure to xylazine and fentanyl-xylazine combinations in pregnancy on maternal, perinatal, and neonatal outcomes are unknown. In 2023, our Perinatal Addiction Consultation and Education Service (PACES) at Magee- Women’s Hospital, the largest maternity hospital in Pennsylvania, noticed a sharp rise in clinical evidence of xylazine exposure among our pregnant patients admitted to our hospital initiate treatment with medications for opioid use disorder (OUD). This has posed new challenges related to the initiation and continuation of medications for opioid use disorder (MOUD, e.g. buprenorphine and methadone) which is particularly concerning, as these medications significantly reduce the risk of overdose and preterm birth in pregnant populations with OUD. The goal of this research is to better understand the prevalence and clinical sequelae of xylazine exposure in pregnancy and explore the effects of xylazine exposure on outcomes among PPWUD and their infants. To achieve this goal, we will conduct a mixed-methods, prospective cohort study among PPWUD at risk of xylazine exposure and utilize health record (EMR) data, urine toxicology testing, and person-reported quantitative and qualitative data to (a) comprehensively evaluate and compare differences in healthcare utilization patterns and outcomes among PPWUD, with and without xylazine exposure, (b) understand the ways in which xylazine exposure may be shaping the lived experiences of patients, and (c) inform the development of future interventions to minimize the risk of adverse outcomes associated with xylazine exposure among pregnant populations.