Who keeps using cannabis after becoming pregnant—and why?

Cannabis use during pregnancy is increasing; however, the prevalence and correlates of cannabis use transitions between preconception and early pregnancy (e.g., persistent use, new uptake, discontinuation) are understudied. Data were from a prospective cohort of United States and Canadian residents trying to conceive who completed online questionnaires during preconception (every 2 months for up to 12 months) and early pregnancy (<12 weeks gestation). Among 9,200 participants who conceived between 2013-2025, we examined associations of sociodemographic characteristics, preconception behaviors, and nausea and vomiting during pregnancy (NVP) with: a) any past-month cannabis use in pregnancy; b) persistent cannabis use (vs. discontinuation) among participants using cannabis during preconception; and c) new uptake of cannabis (vs. persistent nonuse) among participants not using cannabis during preconception. In the full sample (n = 9,200), 284 (3.1%) reported persistent cannabis use, 911 (9.9%) discontinued use, 45 (0.5%) reported new uptake, and 7,960 (86.5%) reported persistent nonuse between preconception and early pregnancy. Among individuals using cannabis during preconception (n = 1,194), 23.8% continued use in pregnancy; among preconception daily cannabis users (n = 8,006), 54.8% continued use in pregnancy. Lower education and income, being unmarried, age <25 years, and history of diagnosed depression and/or anxiety were associated with any cannabis use, persistent use, and new uptake during pregnancy. Preconception alcohol and cigarette use were associated with any cannabis use but not persistent use in pregnancy. NVP was inversely associated with any cannabis use, persistent use, and new uptake during pregnancy. Findings highlight a need for cannabis cessation interventions during preconception and early pregnancy, particularly for reproductive-aged individuals with comorbid mental health issues who use cannabis frequently.