Abstract Background and Aims: Cannabis use is increasingly common among pregnant individuals and might be a risk factor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We aimed to test whether prenatal cannabis use is associated with increased risk of SARS-CoV-2 infection during pregnancy. Design: This is a retrospective cohort study. Setting: The study was conducted in California, USA. Participants: A total of 58 114 pregnancies (with outcomes from 5 March 2020 to 30 September 2021) among 57 287 unique pregnant women aged 14–54 years who were screened for prenatal substance use, enrolled in Kaiser Permanente Northern California (KPNC) (a health-care...