The American College of Obstetricians and Gynecologists recommends universal screening for tobacco, alcohol, and drug use as a part of routine prenatal care. However, little is known about the prevalence of prenatal substance use screening or factors that may contribute to differential rates of screening during prenatal care. This study aimed to describe the prevalence of prenatal substance use screening by substance, year, state, and state-level prenatal substance use policies and to examine individual-level factors associated with receipt of screening. We analyzed 2016 to 2018 data from 103,608 women participating in the Pregnancy Risk Assessment Monitoring System, a population-based survey among women with recent live births. The Pregnancy Risk Assessment Monitoring System survey sampling weights were applied to all analyses. We described the percentage of individuals asked by a healthcare worker about substance use during a prenatal care appointment by substance, year, and state. Using chi-squared tests, we examined differences in the prevalence of screening by state-level prenatal substance use policies, including policies regarding classification of prenatal substance use as child abuse or neglect, mandatory testing or reporting of prenatal substance use, and targeted treatment funding and access for pregnant individuals with substance use disorders. Finally, we estimated the association between individual-level characteristics and receipt of prenatal substance use screening using logistic regression, controlling for year and state fixed effects and accounting for missingness using multiple imputation. In 2018, approximately 95% individuals reported being asked about cigarette or alcohol use during a prenatal care appointment, whereas only 80% reported being asked about drug use. The percentage of individuals who were asked about substance use during a prenatal care appointment increased overall between 2016 and 2018, with variability across states. For all substances, states with laws designating prenatal drug use as child abuse or neglect had lower prevalence of screening, whereas states with laws mandating providers to test for substance use in pregnancy had higher prevalence of screening. Several individual-level characteristics were associated with increased odds of reported prenatal substance use screening for one or more substances, including being younger, less educated, unmarried, Black (vs White), non-Hispanic, or publicly insured (vs privately insured), receiving adequate prenatal care, and having a history of prepregnancy cigarette use. Our study finds that despite recommendations for universal prenatal substance use screening, there are differences in who is actually asked about substance use during prenatal care appointments. This may be influenced by state-level prenatal substance use policies and selective screening approaches in which certain individuals are more likely to be asked about substance use during their prenatal care appointment. A better understanding of the repercussions of selective screening approaches on outcomes and the roles that policies, systems, and provider biases play in perpetuating these approaches is needed to advance guideline implementation efforts in prenatal care settings.