The Effects of Food Stamp Benefits on Weight Gained by Expectant Mothers

Year: 2007

Research Center: Institute for Research on Poverty, University of Wisconsin-Madison

Investigator: Baum, Charles L.

Institution: Middle Tennessee State University

Project Contact:
Charles L. Baum II
Economics and Finance Department
Middle Tennessee State University
P. O. Box 27
Murfreesboro, TN 37132
Phone: 615-898-2527


The Food Stamp Program (FSP) seems to have been successful at increasing the food consumption and nutrient intake of recipients. Consequently, the FSP may have also resulted in weight gain among its low-income recipients, which would be a concern because many Americans are already overweight and obese. The effects of food stamp benefits (FSBs) on weight of pregnant women are likely different because weight gain is not necessarily a detrimental, unintended side-effect for them. Instead, this subgroup, perhaps unlike any other, is encouraged to gain at least some weight while pregnant. The FSP may facilitate recommended weight gain for low-income pregnant women by providing additional resources for food consumption and nutrition. A portion of these women might otherwise be unable to achieve desired pregnancy weight-gain goals due to financial constraints.

This study examines the effects of the FSP on the amount of weight gained by expectant mothers during their pregnancy using 1979-cohort National Longitudinal Survey of Youth data. The analysis is focused on a relatively homogeneous sample of low-income expectant mothers and controls for possible omitted variable bias using a discrete factor random effects estimator. Also estimated are a set of models examining whether expectant mothers gain an ideal amount of weight while pregnant, more weight than recommended, or less weight than recommended based on pre-pregnancy body mass index (BMI). This is important because expectant mothers who are underweight pre-pregnancy are recommended to gain more weight while pregnant than those who are overweight pre-pregnancy. The project includes supplemental sets of models that (1) control for gestation length, (2) separately examine first-time expectant mothers, (3) simultaneously examine participation in the Special Supplemental Program for Women, Infants, and Children (WIC), (4) control for other pregnancy behaviors, (5) control for receipt of FSBs pre-pregnancy, and (6) examine the effects of food stamp receipt for each trimester.

Examining the effects of FSBs on pregnancy weight gain is important because medical researchers have found evidence that poor infant health (proxied by low birth weight, preterm delivery, and infant mortality) is more likely when an insufficient amount of weight is gained during the pregnancy. Further, health at birth has been found to influence later health and development. Perhaps as a consequence, Healthy People 2010, through which the U.S. Department of Health and Human Services specifies the Nation’s health objectives, calls for decreasing the prevalence of low birth weight to a maximum of 5 percent from a current estimate of roughly 7.5 percent. Additionally, examining the effects of FSBs on pregnancy weight gain is important because researchers have found evidence that mothers who gain too much weight while pregnant are more likely to be overweight or obese postpartum.

Results indicate that FSBs have a marginally significant positive effect on pregnancy weight gain and significantly decrease the likelihood that low-income expectant mothers gain an insufficient amount of weight while pregnant. Further, FSBs appear to do nothing to exacerbate excessive weight gain. Providing FSBs to low-income expectant mothers during each month of their pregnancy is predicted to decrease the probability of gaining an insufficient amount of weight by an average of about 4 percentage points. To put this impact in perspective, suppose the Centers for Disease Control and Prevention’s estimates for the prevalence of low birth weight are relevant for this project’s sample of low-income expectant mothers—13.5 percent of expectant mothers who gain too little weight while pregnant have low birth weight babies, whereas only 6.2 percent of expectant mothers who gain a sufficient amount of weight do. If roughly 32 percent of low-income women gain an insufficient amount of weight and the rest gain a sufficient amount of weight, then it is expected that about 8.5 percent of this sample’s births will be of low birth weight. However, if FSBs were provided to the expectant mothers in this sample, then the results presented in this paper predict that the prevalence of insufficient pregnancy weight gain would decrease to about 28 percent. Now, a bit less than 8.25 percent of this sample’s births would be predicted to be of low birth weight. Thus, FSBs could potentially decrease the prevalence of low birth weight among low-income women by about a fourth of a percentage point. This would achieve among low-income women about 10 percent of the reduction in low birth weight called for by Healthy People 2010.

Direct inquiries about this study to the Project Contact listed above.