BACKGROUND: The association between economic insecurity and mental health among low-income pregnant people is understudied. We examined the relationship between economic insecurity and perinatal stress, anxiety, and depressive symptoms among a low-income, racially/ethnically diverse study population, and differentiated associations by nativity status. METHODS: We used cross-sectional data from the EMBRACE Study that enrolled Medi-Cal (California's Medicaid program) eligible pregnant people in the Central Valley region of California. Economic insecurity was assessed through measures of food insecurity, low financial well-being, inability to pay an emergency expense, inability to pay bills, fear of eviction, and history of homelessness. We examined the association of these measures with perceived stress (Perceived Stress Scale), generalized anxiety symptoms (Generalized Anxiety Disorder-7), and depressive symptoms (Patient Health Questionnaire-9), adjusting for age, relationship status, and education level. We also examined effect measure modification by nativity among the Latinx population. We report the estimated differences and 95% confidence intervals for each exposure and outcome. RESULTS: In our sample of 674 participants, we observed associations between economic insecurity and mental health. Among the 24 models, 15 showed medium to large effects (>
0.35 standard deviation differences) and only three showed negligible effect sizes. Across all outcomes, we observed a stronger relationship between economic insecurity and mental health for U.S.-born Latinx people compared with their foreign-born (93% Mexico-born) counterparts. CONCLUSION: We found low-income pregnant people experience significant economic insecurities that may impact mental health adversely. Programs that increase economic supports during pregnancy may serve as important maternal mental health interventions, especially among racial/ethnic minoritized groups.