PURPOSE: This study aimed to evaluate the association of mental health and substance use disorders on the risk of adverse infant outcomes overall and by race/ethnicity and payer. METHODS: We used birth certificates (2017-2022
n = 125,071) linked with state-wide insurance claims (2016-2022
n = 7,583,488) to assess the risk of an adverse infant outcome (i.e., prematurity [<
37 weeks gestation] or low birthweight [<
2,500 g]) associated with "any mental health" or "any substance use" disorder overall, by race/ethnicity, and by payer using diagnoses during the 9 months of pregnancy. We additionally evaluated seven specific mental health conditions and four specific substance use disorders. RESULTS: The rate of having an adverse infant outcome was 13.4%. Approximately 21.5% of birthing individuals had a mental health condition, and 8.7% had a substance use disorder. We found increased adjusted risk of an adverse infant outcome associated with having a mental health condition overall (aRR: 1.28
95%CI: 1.23-1.32) and for all racial/ethnic groups and payers. We additionally found increased risk associated with substance use disorder overall (aRR: 1.32
95%CI: 1.25-1.40) and for White, Black, privately-covered, and Medicaid-covered individuals. There was increased risk associated with six of seven mental health and three of four substance use disorders. CONCLUSIONS: Given the risk of adverse infant outcomes associated with mental health and substance use disorders across racial/ethnic groups and payers, our findings highlight the critical importance of policies and clinical guidelines that support early identification and treatment of a broad spectrum of mental health and substance use disorders throughout the perinatal period.