You were already blaming your mother for ruining your life—but now there's proof! Researchers from The Children's Hospital of Philadelphia and the University of Pennsylvania School of Medicine published a study this week in the American Journal of Clinical Nutrition demonstrating that obesity in children can be directly linked to maternal weight gain. In short, women who put on more than an advisable amount of weight during pregnancy are much more likely to have overweight children—48 percent more likely, in fact. The highest risk of obesity was found among children of women who were overweight when they became pregnant, and also gained excessive weight while pregnant.
Whether the link is causal is open to further research, but researchers think that excess weight may change the environment in the womb itself. "The earliest determinants of obesity may operate during intrauterine life, and gestational weight gain may influence the environment in the womb in ways that can have long-term consequences on the risk of obesity in children," Brian Wrotniak, leader of the study from the Children's Hospital of Philadelphia and the University of Pennsylvania, said in a statement.
The study used statistics gathered between 1959 and 1965 as part of a large study of cerebral palsy. The original research had gathered information on the weight, growth, and socioeconomic situations of over 10,000 mothers and babies. This treasure-trove of information was mined by the University of Pennsylvania researchers. It allowed them to correlate maternal weight both before and during pregnancy with the children's weight at age seven.
Yet the era in which the data was collected means that the results are somewhat uncertain. Of the women in the study, a mere 11 percent gained excessive weight while pregnant, while 65 percent gained insufficient weight—a function of the changes in the American diet over the last 40 years. Currently, the researchers point out, almost half of American pregnant women exceed weight-gain recommendations during pregnancy (in this increasingly obese nation, this trend is hardly surprising). While researchers hope that this study can help the push for improved education on the subject of gestational weight-gain, there is still confusion about how much weight is really safe. Current recommendations for women starting at a healthy weight allow a gain of 25 to 30 pounds during pregnancy, according to the Institute of Medicine, a private organization that advises government agencies on health issues and policy. Women who are already overweight when they become pregnant should only gain 15 pounds. But even these recommendations are currently under review as being potentially excessive, particularly given the frequency with which they are exceeded.
The upshot: It's not yet clear why there's a link between maternal weight-gain and childhood obesity, but it is clear that there is one. But rather than call your mother and tell her your beer gut is all her fault, why not start a sensible weight-loss program instead.