March of Dimes Gives U.S. "C" Grade In Premature Birth Report Card

Last year, the national premature birth rate reached the lowest it's been in a decade.

Still, the March of Dimes has given the U.S. a "C" grade in its annual premature birth report card.

In 2011, the pre-term birth rate was 11.7 percent. That's down from a high of 12.8 percent in 2006.

Just four states earned an "A" for their preemie prevention efforts -- Maine, New Hampshire, Oregon and Vermont.

Forty-five states and Washington D.C. improved their pre-term birth rates last year.