In an article in JAMA, Corsi and colleagues¹ present the results of a retrospective cohort study of 661 617 women designed to assess associations between maternal cannabis use during pregnancy and adverse obstetrical and birth outcomes. In a matched analysis designed to control for confounding, the investigators compared 5639 self-reported cannabis users with 92 873 nonusers and found elevated rates of preterm birth (defined as gestational age <37 weeks) among those who reported cannabis use. Specifically, the rates of preterm birth in the matched cohort were 10.2% vs 7.2% (risk difference, 2.98% [95% CI, 2.63%-3.34%]; relative risk, 1.41 [95% CI, 1.36-1.47]). While similar risks were observed for small-for-gestational-age birth and placental abruption, there appeared to be a small protective association between cannabis use and preeclampsia and gestational diabetes. In another article in JAMA, Volkow and colleagues² report findings on cannabis use among 4400 pregnant women and 133 900 nonpregnant women aged 12 to 44 years who participated in the National Survey on Drug Use and Health from 2002 to 2017. The authors documented an increase in the adjusted prevalence of cannabis use during pregnancy from 3.4% in 2002 to 7.0% in 2017—almost of all which appeared to be explained by nonmedical use.²