Assessment of Marijuana Use During Pregnancy and its Effects on Neonatal Outcomes
Authors: Sheedy Kassidy , Wilson Teresa , Groesch Kathleen , Diaz-Sylvester Paula , Delfino Kristin , Unal E. Ramsey , Nelson Erica 
Published: July 2024

Background: According to the American College of Obstetricians and Gynecologists (ACOG), marijuana is the most used drug during pregnancy, and its self-reported prevalence ranges from ~2% to 7%. ACOG currently recommends against marijuana use during pregnancy due to inconclusive data regarding its safety and health effects. However, we know that THC readily crosses the placenta and can reach high fetal concentrations on repeated exposures. Several reports have linked adverse infant outcomes, such as low birth weight and abnormal neurological development, to marijuana use in pregnancy. Yet, many pregnant women continue to use marijuana throughout gestation as they believe it is safe, highlighting the role that education on marijuana use in pregnancy may aid in decreasing its usage. Furthermore, the growing legalization of marijuana may lead to further increase in marijuana use during pregnancy.

Purpose: We aimed to identify the reported use of marijuana during pregnancy in our patient population, prior to legalization, and examine its effects on maternal and neonatal outcomes. We hypothesized that those who reported using marijuana during pregnancy would have higher rates of maternal complications and adverse neonatal outcomes.

Methods: A retrospective chart review (IRB #21-823) was conducted which included pregnant women and their neonates who were admitted and delivered in 2019 at HSHS St. John’s Hospital in Springfield, Illinois to assess marijuana use prior to legalization and to investigate neonatal outcomes of infants who were exposed to marijuana, including the need for respiratory support or assisted ventilation after delivery. Other data extracted included demographic characteristics, the mother’s medical and obstetrical history, intrapartum and postpartum events and all documented substance use during pregnancy including tobacco, marijuana and illicit drugs. A logistic regression was used to assess marijuana use as a predictor of respiratory outcomes in infants. Odds ratios with 95% confidence intervals (CI) are reported.

Results: In our study, 599 charts were reviewed. Of those, 69 reported marijuana use during pregnancy, or 11.5%, which importantly, is higher than the reported national average of 2-7%. Previous studies have shown a high correlation between marijuana, tobacco and illicit drug use. Additionally, studies have demonstrated that tobacco and illicit drug use result in poor neonatal outcomes. Therefore, we focused on a subpopulation of mothers who only reported marijuana use during pregnancy to remove these confounders. As a result, 112 subjects were removed from the analysis who reportedly used tobacco and/or other illicit drugs in addition to marijuana in order to exclusively focus on the effect of maternal marijuana use on neonatal outcomes. In this subpopulation of 477 subjects, the rate of marijuana use was 5.5% (lower than the overall population), but the effects of marijuana on neonatal outcomes was found to be significant. Demographics were as follows: mean age 28.2 ± 0.25 years; race, ethnicity: 76% White, non-Hispanic and 23% were other (i.e., African American/black, Asian, native Hawaiian/pacific islander, white and Hispanic, non-white and Hispanic or another race). In this subpopulation, admission to the NICU and small for gestational age were not significantly different between marijuana users and non-users. However, marijuana users did have higher odds of preterm birth (OR=3.8, CI: 1.5-9.6; p=0.004). Additionally, marijuana users had increased odds of having an infant that required respiratory support (OR=3.9, CI: 1.4-10.3; p=0.005) and assisted ventilation (OR=4.6, CI: 1.6-13.1; p=0.003). Yet, no adverse maternal outcomes were associated with exclusive marijuana use.

Conclusion: Rates of marijuana use during pregnancy in our population is higher than the reported national average. Moreover, infants whose mothers exclusively used marijuana during pregnancy experienced higher rates of neonatal complications. Thorough screening and counseling regarding marijuana use in pregnancy and during breastfeeding is recommended, although there is no uniform process at this time. Implementing a standardized screening methodology and approach to education on the adverse neonatal effects of marijuana use in pregnancy during prenatal visits may be an effective intervention to improve neonatal outcomes in our patient population. This education is of particular importance in light of the recent legalization of marijuana.