Certain Mothers More Likely to Give Cow’s Milk Too Soon

June 2, 2010

Although many adults drink cow’s milk, it can be harmful to infants’ health. A new study by Penn State and the Institute for Children and Poverty (in New York City) has found that certain low-income mothers are more likely than others to introduce cow’s milk too soon and in doing so, they may be putting their children at risk for health complications.

This was the first time researchers analyzed WIC enrollment by trimester of pregnancy; past studies have only looked holistically at whether or not women had enrolled in the program. The study is helping researchers to better understand the critical time period in which proper nutrition can be reinforced in low-income women, which will have lasting effects in improving their children’s health.

The study showed that women who enrolled in WIC during their first or second trimester of pregnancy—from week one to week twenty-seven—were far less likely to introduce cow's milk too soon than women who enrolled in WIC during their third trimester or women who did not enroll in WIC at all.

“What this study tells us is that if we intervene early by enrolling low-income women in WIC earlier on in their pregnancies, it will be healthier for the babies,” says Dr. Daphne Hernandez, assistant professor of human development and family studies at Penn State and a researcher on the study.

The American Association of Pediatrics recommends that children not drink cow's milk before their first birthday. In addition to being difficult for infants to digest, cow's milk is much lower in iron than breast milk and formula, which means that infants who are fed cow's milk are at an increased risk for developing anemia or other disorders related to iron deficiency. Hernandez hypothesizes that women who enter WIC by their second trimester may be influenced by dietary information provided to them by WIC.

The study, which drew upon data from the Early Childhood Longitudinal Study, Birth Cohort (a nationally representative longitudinal study of children born in 2001), also found that low-income mothers were far more likely to formula feed rather than breastfeed their infants. Breast milk has benefits over formula and cow’s milk; it contains antibodies that can boost infants’ immunity, it can provide emotional benefits for both baby and mother, and it can help mothers lose weight gained during pregnancy. Because of the evidence for the positive effects of breast milk, WIC encourages mothers to breastfeed. However, Hernandez believes that the low rate of breastfeeding among WIC participants is related to the lack of proper facilities in low-wage jobs to pump breast milk.

“We need to rethink the environment of low-wage jobs by taking a closer look at who is being hired and what public programs are available to them to see if there’s a disconnect between low-wage job facilities and advice that is delivered by public programs. Right now, we really don’t make it feasible for low-income women to pump breast milk during the day. If employers provided better facilities for pumping, it could increase the rates of breastfeeding among low-income women and possibly alleviate some of health issues,” says Hernandez.

Hernandez believes that both doctors and employers can learn from this study and help provide access and information to mothers that could improve their infants’ health. “If doctors know that a pregnant patient is economically disadvantaged, they can help get the patient enrolled in WIC sooner. It can be as simple as providing them an application form or showing them a list of grocery stores that accept WIC dollars,” she says.

The study was funded by the U.S. Department of Agriculture and the Robert Wood Johnson Foundation, and its findings were published in the May issue of the Journal of the American Dietetic Association.


Editors: Daphne Hernandez can be reached at dch19@psu.edu. For additional information, please contact the College of Health and Human Development Office of College Relations at 814-865-3831 or healthhd@psu.edu.