12:02AM EST November 13. 2012 - For the fifth consecutive year, the preterm birthrate in the USA continued its slow but steady downward trend, good enough to earn a "C" on a new March of Dimes report card.

The nation's premature birthrate is 11.7% of all live births — the lowest in a decade, according to figures from the National Center for Health Statistics. The March of Dimes has set a goal of 9.6% by 2020.

"We're on the right track," having reversed a trend that included increases every year for decades," says Jennifer Howse, president of the non-profit pregnancy and baby health group. Its 9.6% goal reflects the adoption of measures such as getting mothers to stop smoking and providing access to prenatal care.