PRINCETON, NJ--A study of 41,133 mothers and their children in Arkansas shows that high pregnancy weight gain increases the risk of obesity in those children through age 12. The findings, published Oct. 1 in PLoS Medicine by Princeton University, suggest pregnancy may be an especially important time to prevent obesity in the next generation.
"Excessive weight gain during pregnancy could have a significant effect on future obesity among children," said study author Janet Currie, Henry Putnam Professor of Economics and Policy Affairs and director of the Center for Health and Wellbeing in the Woodrow Wilson School.
Programs to limit pregnancy weight gain could help prevent some cases of childhood obesity. Pregnancy is a good time to target obesity prevention programs, because women may be especially motivated to change their health behaviors," Currie said.
Researchers have previously observed a familial tendency toward obesity. Children with mothers who are obese or gain too much weight during pregnancy are more likely to be obese themselves. However, this relationship may be due to confounding factors such as shared genes, common environmental influences and socioeconomic and demographic considerations, rather than any direct biological effects of maternal diet.
Together with coauthors David Ludwig of Boston Children's Hospital and Heather Rouse of the Arkansas Center for Health Improvement, Currie used a novel study design to examine other causes of childhood obesity. They linked the birth records of mothers with two or more children to school records that included the child's body mass index (BMI) at an average age of 11.9 years and then made statistical comparisons between siblings.
Comparing siblings minimizes the conventional sources of confounding, because, on average, siblings have the same relative distribution of obesity genes, the same home environment and the same socioeconomic and demographic influences.
The current study extends results of an earlier study by Currie and Ludwig, which showed that excessive weight gain in pregnancy increased the birth weight of the infant. The effect of maternal weight gain apparently continues through childhood and accounts for half a BMI unit, or about 2 to 3 lbs., between children of women with the least to the most pregnancy weight gain.
"Excessive weight gain during pregnancy could be contributing to the obesity epidemic," said Currie. "Children whose mothers gained too much weight during pregnancy—that is 40 lbs. or more—had an 8 percent increased risk of obesity."
Other collaborators include, from Boston Children's Hospital, David S. Ludwig, and, from the University of Arkansas, Heather L. Rouse.
The study, "Pregnancy Weight Gain and Childhood Body Weight: A Within-Family Comparison," was first published online Oct. 1 in PLoS Medicine. The collection of birth records and BMI data was supported funds provided from the state of Arkansas. Data analysis was supported by subcontracts from the National Institutes of Diabetes and Digestive and Kidney Diseases and from Princeton's Center for Health and Wellbeing. This work was also supported in part by a grant from the New Balance Foundation.
Journal
PLoS Medicine