The Differential Impacts of Medicaid Expansion on Cesarean Births by Race and Ethnicity

• In Event: Revisiting Medicaid Expansion: Uneven Effects Across Patients, Providers, and Other Insurance Markets

Abstract

We examine how the Affordable Care Act’s Medicaid expansion impacted cesarean delivery, focusing on low-risk nulliparous, term, singleton, vertex (NTSV) births and heterogeneity by race and ethnicity. Using U.S. National Vital Statistics System microdata from 2011–2019 and treating 2014 as the policy implementation year, we analyze over 16 million births, estimating difference-in-differences models with county and year fixed effects. To isolate the insurance-coverage channel, we instrument Medicaid-covered delivery with a Bartik-style shift-share measure based on counties’ pre-expansion self-pay birth shares interacted with post-expansion exposure.Overall, Medicaid expansion had no statistically significant effect on cesarean delivery across our national sample. However, this overall estimate masks important heterogeneity. Among non-Hispanic Black births, cesarean delivery increased by approximately 3.8 percentage points, with the largest effects concentrated among NTSV births. We find no statistically significant NTSV effects for non-Hispanic white or Hispanic births in our difference-in-differences models. For Medicaid-covered births, NTSV cesarean delivery rises by 1 percentage point overall, while cesarean delivery declines among non-Hispanic white births.

Our shift-share results suggest distinct mechanisms across racial and ethnic groups. Among Hispanic NTSV births, Medicaid-paid delivery increases cesarean use. This interpretation is reinforced by first-stage evidence showing that Hispanic births became more likely to be covered by Medicaid after expansion, strengthening the Bartik-style coverage channel. By contrast, IV estimates for non-Hispanic Black births are near zero, suggesting that post-expansion increases are not driven by Medicaid coverage expansion alone. Our findings indicate that insurance expansions can influence obstetric practice through multiple mechanisms and may have different implications across populations.Insurance expansions should be accompanied by ongoing monitoring of NTSV cesarean delivery as a core quality metric that is stratified by race and ethnicity. Health systems and policymakers should pair coverage expansions with delivery-system interventions that address equitable practice patterns and take the delivery preferences of mothers into account.JEL Codes: I13, I18, H51

Author

• Hyesung Oh, California State University, Long Beach
  Presenting Author