Frequency of Fentanyl-Adulterated Street Drugs Consumed by Mothers with Substance Use: The Value of Umbilical Cord Testing

Reports indicate that street drugs are frequently adulterated with fentanyl. However, standard urine drug toxicology may not detect fentanyl, and neonates with prenatal fentanyl exposure often experience severe withdrawal. This study aimed to determine the frequency of fentanyl-adulterated street drugs consumed by mothers with substance use disorders (SUD) using umbilical cord tissue toxicology (UCT).This retrospective observational study (2020-2022) analyzed mothers with SUD and their neonates, utilizing UCT to confirm fentanyl exposure. Additionally, we compared maternal characteristics between those who acknowledged fentanyl use during pregnancy and those who did not, along with neonatal outcomes.Among 353 infants born to 342 mothers with opioid use, 21.8% (77/353) had in-utero fentanyl exposure confirmed by UCT. Notably, 54% (40/74) of mothers in the fentanyl-positive group did not acknowledge fentanyl use. However, these mothers more frequently reported using other substances, including marijuana (<i>p </i>< 0.01) and cocaine (<i>p </i>< 0.03), suggesting fentanyl adulteration in street drugs. Umbilical cord fentanyl concentrations were similar between groups, though variance was higher among those who did not report fentanyl use, indicating potential inconsistent exposure. No significant differences were observed in neonatal characteristics.Our study highlights the high frequency of prenatal fentanyl exposure due to adulterated street drugs used by mothers. Although the infant's characteristics and the severity of NOWS were similar in both groups, long-term outcomes may depend on UCT fentanyl concentrations. Therefore, umbilical cord drug screening is a crucial tool for detecting fetal exposure to fentanyl and appropriate neonatal assessment and intervention. · Fentanyl, a potent synthetic opioid, is increasingly found in street drugs, often unbeknownst to users.. · Mothers struggling with substance use may be exposed to illicit fentanyl without their knowledge.. · Umbilical cord testing is crucial for identifying substance exposures in newborns.. · Newborn assessment and treatment can differ and impact their short- and long-term outcomes..