A study of over 20 years of birth records has found that women who received State Earned Income Tax Credits (EIC) gave birth to higher weight babies. The effect was strongest in mothers who were age 19-35.

EIC is a refundable tax credit that supplements the income of low wage workers. While some income is necessary to receive the credit, in most states the credit can be taken even if no tax is owed, allowing people who normally wouldn't file a tax return to get a refund.

The study only begins to scratch the surface of the relationship between anti-poverty programs and health.

Low weight babies start life at a severe disadvantage. They're at higher risk of dying during the first year of life, particularly those born under 5.5 pounds. Those who survive tend to do worse in school, are less likely to earn a high school diploma and have lower incomes as adults than their higher birth weight counterparts. For these reasons birth weight is a basic indicator of health. Babies born to poor mothers are much more likely to be low weight than babies born to wealthier mothers.

Little is known about how anti-poverty programs affect children and families beyond raising their income. The study researchers were interested in whether anti-poverty programs had any effect on infant birth weight. They chose to look at state EIC programs because they are among the largest of all current anti-poverty programs and in many states now serve as a partial substitute for the welfare programs that were dismantled in the 1990s.

The researchers confined their study to unmarried mothers with a high school diploma or less. Birth weights were obtained from the 1980-2002 U.S. Natality Detail File, which records nearly every birth in the U.S. It records birth weight directly from birth certificates, not from personal recall. Income and household information was collected from annual surveys of 58,000 rotating households conducted yearly buy the U.S. Census Bureau.

Not only did receiving state EIC result in higher infant birth weights, they also reduced the chance of mothers smoking during their pregnancy.

The study only begins to scratch the surface of the relationship between anti-poverty programs and health. There are certainly reasons other than EIC why states with high participation in EIC programs could be having fewer low weight births. But the study authors think their results offer encouraging evidence that by relieving some of the effects of poverty, state EIC programs are helping women have healthier babies.

An article on the study was published in the August 2010 issue of the American Sociological Review.