Cannabis Use as Determined by Biologic Testing in Maternal and Newborn Urines during a Period of Drug Liberalization.

Introduction: Cannabis use is common in pregnancy and prevalence of reported past month use have been increasing despite recommendations of abstinence. Our study aimed to evaluate the prevalence of cannabis use in pregnancy using urine drug screens obtained at the time of admission to Labor and Delivery. Methods: De-identified laboratory data from three birthing hospitals located in Maryland were used to determine the percentage of cannabis positive urine toxicology tests among women admitted to Labor and Delivery. Data were collected at each site starting the year that universal urine cannabis testing was instituted. One hospital also performed universal testing of newborns which was contrasted with maternal data there. Results: Overall, 5.7% of the 22,435 maternal and 3.4% of the 8,346 newborn urine toxicology tests and were positive for cannabis. Trends varied between institutions. When all three institutions were combined, the percent of positive urine toxicology tests was unchanged between 2016 and 2018. At Site 1 between 2014 and 2018, the percentage of cannabis positive urine toxicology tests increased from 5.7% to 9.9% and newborn tests increased from 1.7% to 3.4%. Only 27.7% of the neonates born to women with positive screens also had a positive screen at the time of birth. Conclusions: Prevalence of cannabis use until the time of delivery vary by location but were largely unchanged over a period of drug liberalization.