Has Medicaid expansion improved birth outcomes?

April 30, 2019

A recent study examines whether expanding Medicaid coverage has impacted rates of low birthweight and prematurity among infants.

Following the Affordable Care Act (ACA), several states expanded Medicaid coverage to improve continuity of care to low-income women regardless of pregnancy status. A recent study in JAMA, evaluated whether Medicaid expansion impacted rates of low birthweight (LBW) and prematurity among infants, both overall and by race and ethnicity. 

For the research, data from the National Center for Health Statistics (NCHS) Statistics Birth Data Files (2011-2016), which represent an estimated 99% of all live births from all 50 states and the District of Columbia, were used. The authors compared birth outcomes among states that had and had not expanded coverage. 

Of the 15.6 million births studied, 8.2 million were white infants, 2.2 million were black, and 3.9 million were Hispanic. Geographically, 8.5 million of the births were from the District of Columbia and 18 states that expanded Medicaid and 17.1 million of the births were from 17 states that did not expand. 

The authors used difference-in-difference (DID) models and difference-in-difference-differences (DDD) models to compare birth outcomes. Four birth outcomes were examined: preterm birth (PTB) (< 37 weeks’ gestation), very preterm birth (VPTB) (< 32 weeks’ gestation), LBW (<2500 g) and very low birth weight (VLBW) (< 1500 g).

In the DID analyses, the authors observed no significant changes in PTB in states with expansion compared to those without. Changes in low birthweight were also not significant. 

However, expansion of Medicaid resulted in a reduction in disparities for black infants relative to white infants for all four PTB outcomes. PTB fell by-0.43 percentage points [95% CI, -0.84 – -0.02], P= .05), VPTB by -0.14 percentage points [95% CI, -0.26 to -0.02],P= .03), LBW by -0.53 percentage points [95% CI, -0.96 to -0.10], P= .02), and VLBW (-0.13 percentage points [95% CI, -0.25 to -0.01], =.04). No significant changes were observed in Hispanic infants. 

Overall, state Medicaid expansion was not significantly associated with differences in rates of LBW or PTB. For black infants, however, there were significant improvements compared to white infants in states that made the change in coverage. Because black infants die of complications associated with prematurity and LBW at 3.9 times the rate of white infants (257.6 vs 66.3 per 100,000 live births in 2016), the expansion efforts could be helping those most at risk.