Children are getting fatter and fatter; the prevalence of obesity has risen rapidly in recent decades. Many children are already obese before they even start kindergarten. Researcher Robert Whitaker, who carried out this study when he was at the University of Cincinnati, looked at whether preschoolers' obesity is related to their own mothers' weight, using data on women and children in the Special Supplemental Nutrition Program for Women, Infants, and Children (better known as WIC), a federal program that gives food and nutritional counseling to low-income women during pregnancy and their children under 5.

What the researcher wanted to know: Are preschoolers whose mothers were obese early in pregnancy likely to be obese themselves?

What he did: Whitaker used data on women and children enrolled in WIC for whom he could get information spanning the time from the first trimester of pregnancy until the children were between 2 years and 4 years 11 months old. The children were born between 1992 and 1996; he got useful data for 8,494 pairs of children and mothers. More than 30 percent of the women were obese in the first trimester of pregnancy.

What he found: Two- to four-year-old children whose mothers were obese in the first trimester of pregnancy were about 2.5 times more likely to be obese than children whose mothers were normal weight early in pregnancy. Nearly 1 in 4 of the obese mothers' children were obese by the age of 4, compared with fewer than 1 in 10 of normal-weight mothers. Obese women's babies were twice as likely to weigh more than average at birth, too.

What the study means to you: For many children, obesity starts before they're even born. Whitaker writes that it may be possible to prevent obesity through WIC, since the program reaches so many women and children.

Caveats: The study can't tell how obesity gets passed on—it could be genetics, or effects of the mother's obesity on the environment in the womb, or how the mother shapes her child's eating habits.

Find out more: WIC http://www.fns.usda.gov/wic/

An article on childhood obesity from NIH: http://www.nih.gov/news/

Read the article: Whitaker, R.C. "Predicting Preschooler Obesity at Birth: The Role of Maternal Obesity in Early Pregnancy." Pediatrics. July 2004, Vol. 114, No. 1, pp. e29-e36.

Free abstract online: http://pediatrics.aappublications.org