A new analysis of federal health data shows that Medicaid paid for nearly half of all births in the United States in 2010, a rate that continues to increase.

The federal health care program covered 48 percent of the 3.8 million births that year, jumping from 40 percent in 2008, say researchers from the George Washington University School of Public Health. In only two years, the government entitlement covered 90,000 more women giving birth, as states expand the federal-state health coverage plan.

"As states expand coverage, low-income women of childbearing age will be able to obtain more continuous coverage before and between pregnancies," lead investigator Anne Markus, an associate professor of health policy at the university, said in a statement. Markus and her colleagues said the study would help other researchers assess changes to America’s health care system brought by the Affordable Care Act of 2010, also known as Obamacare.

"Now, for the first time, researchers will have a comprehensive baseline that will help them determine how increased access to services might change pregnancies and ultimately birth outcomes," Markus said.

Naturally, Medicaid coverage varied greatly state by state, ranging from a low of one-quarter of births in Hawaii to nearly 70 percent in Louisiana. The generally poorer southern states made greater use of Medicaid in covering births, compared to northeastern and northwestern states. In contrast to Louisiana and other southern states, Medicaid in Massachusetts and New Hampshire covered 30 percent and 39 percent of births, respectively. In Arkansas and Mississippi, more than 60 percent of births were paid for by the federal program.

The researchers said the study would also help analysts to determine the efficacy of the program in reducing childbirth complications and improving the health of women and babies.

"This study gives us a window into the vital role Medicaid plays in maternal and child health," study co-author Cynthia Pellegrini, senior vice president for public policy and government affairs at the March of Dimes, said. "With these data in hand, we'll be able to accurately monitor the impact of Medicaid expansion and other factors on the births covered by state Medicaid programs."

The study provides a useful tool to help researchers chart future progress in lowering the rate of premature births in the U.S., which currently sits at a half-million births per year.

Source: Markus, Anne Rossier, Andres, Ellie, West, Kristina D, Garro, Nicole, Pellegrini, Cynthia. Medicaid Covered Births, 2008 Through 2010, In The Context Of The Implementation Of Health Reform. Women's Health issues. 2013.