Medicaid expansion and risk of eclampsia

Eclampsia is an indicator of severe maternal morbidity and can be prevented through increased prenatal care access and early prenatal care utilization. The 2014 Medicaid expansion under the Patient Protection and Affordable Care Act allowed states to expand Medicaid coverage to nonelderly adults with incomes up to 138% of the federal poverty level. Its implementation has led to a significant increase in prenatal care access and utilization.

This study aimed to assess the association of Medicaid expansion under the Affordable Care Act with eclampsia incidence.

This natural experiment study was based on US birth certificate data from January 2010 to December 2018 in 16 states that expanded Medicaid in January 2014 and in 13 states that did not expand Medicaid during the study period. The outcome was eclampsia incidence, the intervention was the implementation of the Medicaid expansion, and the exposure was state expansion status. Using the interrupted time series method, we compared temporal trends in the incidence of eclampsia before and after the intervention in expansion vs non-expansion states with adjustments for patient and hospital county characteristics.

Of the 21,570,021 birth certificates analyzed, 11,433,862 (53.0%) were in expansion states and 12,035,159 (55.8%) were in the postintervention period. The diagnosis of eclampsia was recorded in 42,677 birth certificates or 19.8 per 10,000 (95% confidence interval, 19.6-20.0). The incidence of eclampsia was higher for Black people (29.1 per 10,000) than for White (20.7 per 10,000), Hispanic (15.3 per 10,000), and birthing people of other race and ethnicity (15.4 per 10,000). In the expansion states, the incidence of eclampsia increased during the preintervention period and decreased during the postintervention period; in the nonexpansion states, a reverse pattern was observed. A statistically significant difference was observed between expansion and nonexpansion states in temporal trends between the pre- and postintervention periods, with an overall 1.6% decrease (95% confidence interval, 1.3-1.9) in the incidence of eclampsia in expansion states compared with nonexpansion states. The results were consistent in subgroup analyses according to maternal race and ethnicity, education level (less than high school or high school and higher), parity (nulliparous or parous), delivery mode (vaginal or cesarean delivery), and poverty in the residence county (high or low).

Implementation of the Affordable Care Act Medicaid expansion was associated with a small statistically significant reduction in the incidence of eclampsia. Its clinical significance and cost-effectiveness remain to be determined.