Timing of Medicaid Enrollment during Pregnancy and Associated Infant Outcomes

OBJECTIVE: To describe the timing of Medicaid enrollment during pregnancy among Medicaid-insured women in Texas, examine patterns of healthcare utilization following enrollment, and evaluate associations between enrollment timing and infant outcomes. METHODS: Retrospective cohort study of 913,229 deliveries to women aged 15-44 years enrolled in Texas Medicaid between January 1, 2010, and December 31, 2014. Women were classified into five mutually exclusive groups based on timing of first Medicaid enrollment: before conception, first, second, or third trimester, or delivery hospitalization. We evaluated associations between enrollment timing and cesarean delivery, preterm birth, small-for-gestational-age (SGA), and neonatal mortality using Poisson regression with robust standard errors. RESULTS: Overall, 26.4% (n=238,689) of women enrolled in Medicaid before conception, 40.0% (n=364,905) during the first trimester, 14.3% (n=130,568) during the second trimester, 6.1% (n=56,090) during the third trimester, and 13.5% (n=122,977) at delivery. Later enrollment was more common among Hispanic and foreign-born women and among those with a lower mean obstetric comorbidity index. Most women had their first Medicaid-covered healthcare encounter in the same trimester as enrollment, primarily in ambulatory care settings. In adjusted analyses, enrollment before conception was associated with a higher risk of preterm birth (aRR 1.17; 95% CI,1.15-1.18) relative to first-trimester enrollment. Second- and third-trimester enrollment were associated with higher risks of SGA (aRR 1.15 [95% CI,1.12-1.18] and 1.18 [95% CI,1.13-1.22], respectively). CONCLUSION: Medicaid enrollment timing varied across demographic groups and was associated with differences in healthcare utilization and selected infant outcomes. Improving maternal and infant health may require not only timely coverage but also efforts to address structural barriers to Medicaid enrollment and prenatal care access.