Clapp MA, et al. - Researchers sought to determine how the Affordable Care Act's Medicaid expansion affected payment for delivery, early access to prenatal care, preterm birth, and birth weights considered small for gestational age (SGA) They used a difference-in-difference design to evaluate changes in outcomes before and after Medicaid expansion in expansion states, using nonexpansion states as a control group. The study sample comprised 8,701,889 women from 15 expansion states, and 9,509,994 women from 11 nonexpansion states. The analysis suggests the association of Medicaid expansion with increased Medicaid coverage for childbirth in expansion states; they observed similar gains in private coverage in nonexpansion states. No associations were evident with changes in early access to prenatal care, preterm birth, or SGA birth weights.