Background/Objectives: Substance use during pregnancy continues to affect maternal and infant health outcomes globally. Applying the Three Delays Framework, this study evaluates the relationship between substance use and maternal health outcomes in Alabama, focusing on prenatal care health barriers. Methods: This study employed a quantitative design using secondary data from the PRAMS Phase 8 survey (2016–2021) provided by the Alabama Department of Public Health. Prenatal care barriers were classified into three domains: delays in seeking, reaching, and receiving care. Advanced statistical techniques were undertaken, including descriptive statistics, logistic regression, and mediation analysis. An item response theory (IRT) model was applied to derive an underlying characteristic for informational barriers (theta_info). This was incorporated into a structural equation model (SEM) to test whether informational barriers mediate the relationship between substance use and maternal health outcomes. Demographic covariates like age, race/ethnicity, income, BMI were included as controls. Results: Logistic regression results showed that systemic barriers (OR = 1.77, p = .047) and informational barriers (OR = 2.42, p < .001) were significantly associated with adverse maternal health outcomes. Structural barriers and substance use had insignificant direct effects. However, mediation analysis and SEM findings revealed that informational barriers significantly mediated the relationship between substance use and maternal health, with approximately 44% of the effect transmitted indirectly through theta_info. Conclusions: These findings emphasize the critical role of prenatal care barriers like systemic and informational barriers in influencing maternal health outcomes in Alabama. Addressing informational deficits can improve prenatal care and perinatal outcomes.