Invited commentary: Expanding legalization and increasing social acceptability and accessibility of cannabis may potentially be associated with increased use of cannabis among women of reproductive age. Using repeated cross-sectional data from the Pregnancy Risk Assessment Monitoring System (PRAMS) between 2004 and 2018, Skelton and colleagues¹ compared maternal cannabis use at 2 time points during the preconception, prenatal, and postpartum periods among women living in 2 states that legalized recreational use (Maine and Alaska) and 2 that legalized only medicinal use or decriminalized recreational use (Vermont and New Hampshire). The authors used a difference-in-difference analysis over time, contrasting changes in intervention and comparison states, an important strength compared with earlier studies on this topic. Consistent with prior research, results indicated that the prevalence of cannabis use before and during pregnancy increased over time in both intervention and comparison states. In the 2 states that legalized recreational cannabis use, preconception and postpartum cannabis use, but not prenatal use, increased significantly compared with states that did not legalize recreational use....