Xylazine Use in Pregnancy: The Effects of the Fentanyl Adulterant Xylazine on Pregnant Patients and the Developing Fetus.

Objective: A literature review was completed to outline the effects of xylazine on the pregnant patient while raising awareness of the increasing prevalence of opioid use disorder in pregnancy and the increase in adulterants in non-prescribed controlled substances. Data Sources: PubMed and Google Scholar were searched using the key words "xylazine, adulterant," "xylazine, humans," "xylazine, pregnancy," and "xylazine, placenta" to identify the studies evaluating xylazine's effects on humans and the pregnant patient. Study Selection: Studies were included if they provided information on symptoms of xylazine exposure, the prevalence of xylazine in pregnant humans and the hemodynamic effects of xylazine on both human and animal pregnant populations. Animal studies were included given the limited data on xylazine in pregnant humans. Four studies were utilized for background data and five studies were included in the final review of the effects of xylazine on pregnancy. Results: Studies involving humans show that xylazine toxicity can cause respiratory depression, bradycardia, and central nervous system depression. There is evidence of xylazine in human umbilical cord tissue, showing that the fetus is exposed to xylazine. Animal studies show decreased uterine blood flow, increased uterine vascular resistance, and decreased fetal growth in response to xylazine. Conclusions: Due to the limited studies on the effects of xylazine on pregnant populations, providers rely on animal studies for knowledge on xylazine's effects throughout pregnancy. Animal studies suggest an increased risk of adverse effects during pregnancy in response to xylazine. Future studies should focus on the pregnancy outcomes in patients exposed to xylazine to create more robust recommendations for treatment and pregnancy surveillance.