ACA Medicaid expansion and prenatal insurance in low-income women

Lack of insurance may limit patient access to prenatal care. For low-income women, the Affordable Care Act (ACA) and expansion of Medicaid in some states provided a new opportunity for coverage before pregnancy. A new study provides insight into what effect the ACA Medicaid expansion had on preconception insurance coverage among low-income women.

Published in Obstetrics & Gynecology, the study used a quasi-experimental, difference-in-difference design to compare changes in preconception insurance coverage among low-income women living in expansion compared with nonexpansion states before and after the Medicaid expansions. In such a design, longitudinal data are used to compare the effect of an intervention between an exposed and an unexposed group. Differences between the groups are attributed to the intervention. 

The 57,056 women included in the study participated in the Pregnancy Risk Assessment Monitoring System from 2009 to 2015. All had family incomes ≤ 138% of the federal poverty level, meaning that they were newly eligible for Medicaid if they lived in expansion states. Of the participants, 30,495 were from eight states that expanded Medicaid under ACA and 26,561 were from seven states that did not. 

The primary outcome of the study was insurance status 1 month before conception. The researchers performed additional subgroup and sensitivity analyses to test the assumptions of the model and the robustness of the findings.

Before ACA, 30.8% of women in nonexpansion states had Medicaid coverage prior to conception versus 35% after ACA. Of the women in the states where Medicaid was expanded, 43.2% had Medicaid coverage prior to conception before ACA versus 56.8% after the expansion. There was a significantly greater increase in Medicaid coverage in expansion states after the policy implementation (adjusted difference-in-difference estimate +8.6% points, 95% CI 1.1-16.0). 

Rates of preconception uninsurance were 44.2% prepolicy and 34.3% postpolicy in nonexpansion states and 37.4% prepolicy and 23.5% postpolicy in expansion states. Changes in uninsurance did not differ significantly between the two groups in the postpolicy period. Non-Medicaid insurance coverage was 25.3% prepolicy and 30.5% postpolicy in nonexpansion states and 19.4% prepolicy and 19.7% postpolicy in expansion states. 

The authors concluded that Medicaid expansion was associated with increased enrollment in Medicaid before pregnancy among low-income women and “with greater continuity of Medicaid coverage from the preconception to pregnancy period.” To fully assess the effects of the policy change, they said, more years of postpolicy data are needed while noting that their analysis relied on self-reported survey data collected after delivery, which could be subject to recall bias.