OBJECTIVE: Evaluate associations between prenatal cannabis use (PCU) and perinatal outcomes. METHODS: We performed an interval analysis of a prospective cohort study of pregnant individuals with pre-pregnancy cannabis use and negative self-report of nicotine use, comparing those who continued cannabis through pregnancy with those who stopped. Patients underwent interviews and urine drug screening for cannabis and cotinine, a nicotine metabolite, in each trimester. The primary outcome was small for gestational age (SGA) at delivery. Secondary outcomes included antenatal and postpartum complications, mode of delivery, and neonatal outcomes. Secondary analyses included stratification by intensity of cannabis use and urinary cotinine positivity. RESULTS: Birthing persons with PCU differed in age (25.5 vs 27.8 years, p=0.001), body mass index (BMI; 27.4 vs 30.9, p=0.001), area deprivation index percentiles (92% PCU vs 88%, p=0.013), cotinine positivity (42.8% vs 10.8%, p<0.001), Hispanic ethnicity (2% vs 7.2%, p=0.009), and education attainment beyond high school (29.4% vs 50%, p<0.001) compared to controls. Birthing person outcomes did not differ. Risks of SGA and other neonatal outcomes did not differ when adjusted for confounders on initial analysis, or with stratification by intensity of cannabis use. Despite negative self-report for nicotine, 42.8% of PCU patients tested positive for cotinine (PCU+c). PCU+c was associated with increased risk of SGA and birthweight less than the 5th percentile, compared to PCU cases without nicotine exposure (17.4% vs 8.3%, aRR 2.7 [1.21-5.38], 35.8% vs 18.6%, aRR 2.4 [1.51-3.48]), and controls (35.8% vs 12.9%, aRR 2.75 [1.64-4.13]). Cotinine-negative PCU patients and controls did not differ. CONCLUSION: PCU was not independently associated with adverse birthing person outcomes. Many patients demonstrated nicotine exposure, either via inadvertent exposure or undisclosed use. While neonates exposed to cannabis alone did not differ from unexposed neonates, those exposed to both cannabis and nicotine were at increased risk of SGA.

The authors have declared no competing interest.

This study was funded by NIH R01DA046224, Rogers/Agrawal.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The Washington University in St. Louis Institutional Review Board (ID 20180001) gave ethical approval for the Cannabis Use During Development and Early Life (CUDDEL) study.

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All data produced in the present study are currently not available upon request as the larger study is ongoing.