Figure 2. Changes in Prenatal Cannabis Use by Self-Report or Urine Toxicology Before and After Recreational Cannabis Legalization (RCL) Implementation, Stratified by the Pre-RCL Medical Storefront Retail Policy.

Relative rates (RRs) are standardized to age, race and ethnicity, and neighborhood deprivation index of the pregnancies in the overall study sample during 2019. The lines show the fitted regression of the interrupted time series model, the dots show the monthly standardized rates, and the shaded areas represent the 95% CIs of the fitted regression line. Prenatal cannabis use was based on a positive urine toxicology test or self-report conducted as part of standard prenatal care (typically around 8-10 weeks’ gestation).