Study finds WIC program has moderate effect on birth outcomes, but more research is needed

Apr 29 2010

A new study that looked at the effect of the Special Supplemental Nutrition Program for Women, Infants and Children (WIC) to determine the effect on various birth outcomes found that the overall effects were only moderate.

"This is one of several programs for which the evidence of impact is rather limited," said lead author E. Michael Foster. "I'm not ready to say it should be eliminated, but it might be worth having the government pay for a very carefully done study of its impact."

Foster is a professor at the Gillings School of Global Public Health at the University of North Carolina at Chapel Hill. The study appears online in the journal Health Services Research.

Established in 1972, WIC's mission is "to safeguard the health of low-income women, infants, and children up to age 5 who are at nutritional risk by providing nutritious foods to supplement diets, information on healthy eating and referrals to health care." About 8 million women and children receive WIC each year, at a cost of about $5 billion.

Although not a specific target of the WIC mission statement, "WIC has always been justified for its effects on birth outcomes," Foster said. "After all, it includes prenatal nutrition counseling."

WIC should not be judged by its effect on birth outcomes alone, said Joyce Converse, a registered nurse clinician who has worked directly with WIC participants in the high-risk program and with postpartum referrals

"Improving maternal nutrition for the developing fetus at any gestation is a potential benefit," Converse said. "[The study] also does not address the potential benefits of this program after birth."

Researchers looked at six pertinent birth outcomes to ascertain the influence of WIC: (1) neonatal hospitalization in the intensive care unit, (2) birth weight, (3) low birth weight, (4) premature birth before 37 weeks gestation, (5) a maternal report of infant health compared to other babies and (6) whether the infant was small for gestational age.

The researchers used more than one statistical method to analyze information on 3,181 mothers and their children from 1968 to the present.

With one method, they found no statistically significant effects for any of the outcomes studied. This technique accounted for factors such as family income before comparing WIC and non-WIC moms.

However, using the other method, which looked at the effect of the program within families - comparing one child born under WIC to a child born outside of WIC - the researchers found that participation had a significant influence on birth weight and premature birth.

Foster said that the variation in results had to do with the fact that there is no way to assign participation in the WIC program randomly - a hurdle common to many studies that compare groups of people.

"The problem is that we want to say that people are similar enough when they obviously differ in the treatment or exposure that is of interest," Foster said.

Converse, who also is senior vice president of a health care consulting company, said she would like to see further research: "Since the benefits were not profound, I would hope that any cost-benefit of the WIC program would not be decided based on this study, which still has limitations.