Aside from multiple births and the risks of medically assisted reproduction, the March of Dimes points to other factors in premature births such as mothers smoking during pregnancy and access to prenatal care.
Dr. Jennifer L. Howse, president of the March of Dimes, points to four key ways to reduce the preterm birthrate that the NCHS report says could cut the infant mortality rate by one-third.
"We did see a very small decline in the preterm birth rate, from 12.8 to 12.7 percent of live births in 2007. Also, fewer women of childbearing age are smoking, and the nation's late preterm birth rate also declined, although very, very slightly," she says. "I am optimistic that as we see reductions in the risk factors, we will see a reduction in the rate of preterm birth."