Children of married parents less likely to be obese

"Childhood obesity is a significant public health issue in our country, with nearly one-third of all U.S. children ages 2-17 overweight or obese," said Rachel Kimbro, study co-author, associate professor of sociology at Rice and director of Rice's Kinder Institute Urban Health Program. "Despite this, very little research has been conducted to explore the impact of family structure on this epidemic."

In a recent edition of the Journal of Applied Research on Children: Informing Policy for Children at Risk, research by Kimbro and colleagues shows that children living in a traditional two-parent married household are less likely to be obese (17 percent obesity rate) than children living with cohabitating parents, who have a 31 percent obesity rate. The obesity rate is even higher for children living with an adult relative (29 percent), single mother (23 percent) and cohabitating stepparent family (23 percent). The study did not evaluate children of same-sex couples, due to lack of available data. The higher rates for nontraditional parent families were observed even after the researchers accounted for factors associated with childhood obesity, including diet, physical activity and socio-economic status.

The exception to this finding was children living with single fathers or in married stepparent households, who had an obesity rate of 15 percent.

"Previous research has shown that single-father households tend to have more socio-economic resources than single-mother households," Kimbro said. "And since socio-economic status is the single greatest predictor of health, it serves to explain why children in single-father households may be less likely to be obese."

The study, "Family Structure and Obesity Among U.S. Children," examined the obesity rates of children living in traditional and nontraditional family structures in the U.S. The research sample of 10,400 children comes from the Early Childhood Longitudinal Study-Birth Cohort, a nationally representative study of U.S. children and their families designed to provide information on children's development.

Data collection for the study began in 2001. The primary caregivers of the children participated in the first wave of the in-home interviews when their children were approximately 9 months old. Data was subsequently collected when the children were 2 years old, in preschool (approximately age 4) and in kindergarten. The sample included children from diverse socio-economic, racial and ethnic backgrounds as well as an oversample of Asian, Pacific Islander, Alaska Native, American Indian, twins and low-birth-weight children. Forty-six percent of the children were racial or ethnic minorities, 25 percent were poor and 16 percent of the children had mothers without high school diplomas.

The interviews included assessments of the children's height, weight and other measures of development, such as cognitive functioning. The children were organized in eight mutually exclusive categories designed to account for the children's current family structure and the one they were born into.

The authors hope their research will inspire future studies of nontraditional family structures and their impact on health and weight.

"For reasons we cannot fully measure, there appears to be something about people who marry and have a child that is fundamentally different than the other groups, and these factors are also linked to children's weight," Kimbro said.

"Our hope is that this research will encourage further exploration of this topic," said Kimbro's co-author, Jennifer Augustine. "There is substantial research on how family structure matters to other domains of children's development, yet little research on why marriage and other family structure types might matter for children's obesity."

Kimbro and Augustine have already begun to lead this charge with a new project that examines the household-level processes associated with different family structures that may explain differences in young children's risk of obesity.

The research was funded by Rice University and the University of Houston.