Each year, more than 530,000 babies are born before 37 full weeks of gestation, statistics show. About one in eight births in the U.S. is premature. Sixty percent of babies born at 26 weeks of gestation have long-term disabilities, such as chronic lung disease, deafness and neurodevelopmental problems.

Preterm delivery is the leading cause of infant mortality and yet researchers and doctors don’t know what causes it. Premature babies have a higher risk of respiratory problems, neurological diseases, and the risk of early childhood mortality is up to seven times higher for preemies than for babies born at full term with normal birth weight.

According to the first nationwide Premature Birth Report Card, seventeen states earned an F from the advocacy group and there were no As among the grades. The U.S. received a D overall on the March of Dimes’ first state by state report released today.

One state, Vermont, earned a B and ranked at the top with a rate of 9%. The cutoff for an A and the government’s “Healthy People 2010” goal was a preterm birth rate of 7.6% or less.

Eight states received Cs and 23 states received Ds.

In addition to providing state rankings, the March of Dimes report card also analyzes the rates of factors that contribute to premature birth. Risk factors for premature birth include: smoking among mothers-to-be, absence of health insurance for that same group, pregnancy depression.

“Many factors go into both a state's and a nation's premature birth rate,” said Ronald S. Gibbs, MD, a volunteer and medical-expert spokesman for the March of Dimes.

However, the group said there are some solutions that are at hand and some steps that can be done in order to lower the premature birth rate. Among them: increased federal spending for prematurity prevention medical research, expanded access to health coverage for childbearing-age women, smoking cessation programs for mothers-to-be. Pregnant women who have had a previous episode of preterm birth should get weekly shots of the hormone progesterone starting at 16 to 20 weeks' gestation. Studies have shown that this treatment can reduce preterm birth risk by up to one third.

Also, treating pregnancy depression might be an effective way to help prevent these premature births. Research has shown that after taking other risk factors into account (such as mother’s age, education level, and whether the woman had a preterm baby in the past), women with less severe depressive symptoms have a 60 percent higher risk of a premature birth compared to women without “significant” depressive symptoms.

Given this situation, prematurity still remains a major national concern. Infant deaths in the United States continue to surpass other developed countries despite a bigger amount of money spent on health care. Premature birth and low birth weight are two main factors that contribute to more than two thirds of infant deaths.