Most pregnant women wouldn't dream of belting back cocktails or lighting up. But what about that Big Mac and daily Krispy Kreme doughnut? In a Freudian twist, a growing number of researchers now contend that if Junior eventually battles middle-age spread, hypertension, and diabetes, Mom's diet during pregnancy will bear some of the blame.
The notion that nourishment in the womb might trigger serious disease decades later is controversial, but a spate of recent studies adds to the evidence. This month, Kaiser Permanente researchers report in the journal Diabetes Care that children who took in an excessive amount of sugar in the womb—because their mothers' mild diabetes caused high blood glucose levels—were nearly twice as likely to become obese by elementary school as those whose moms had been successfully treated for severe diabetes. Another recent study found that women who followed a high-protein Atkins-style diet had children who much later were unusually sensitive to stress, which is associated with heart disease and diabetes. "The implications of this are enormous," says Daniel Benyshek, an assistant professor of anthropology at the University of Nevada-Las Vegas who has done research on how nutrients affect fetal development. "I think it's a significant factor in the current obesity epidemic."
Programmed. Benyshek and other scientists now believe that after the initial intertangling of DNA at conception, a baby's genes are expressed a certain way—switched off or on—depending on the conditions in utero. Thus, cells may be wired to sock away fat if they're bathed in too many or too few nutrients, for example, or to release it readily for fuel if given just the right amount. Underweight newborns appear to have systems unable to cope effectively with glucose, which makes them more prone to obesity once they're happily enjoying a fast-food lifestyle. "We first found in the 1980s that people who were born at low birth weights to poor malnourished mothers tended to have high rates of heart disease, stroke, and diabetes," says David Barker, a professor of medicine at Oregon Health and Science University in Portland, who was the first to suggest that fetal programming can lead to chronic disease.
More often, nowadays, babies are overnourished—and not only because of the fabled pregnancy cravings. Women who are overweight when they become pregnant, which is becoming increasingly common, risk developing the abnormally high blood glucose levels associated with gestational diabetes. As this sugar-rich blood passes through the placenta, baby adapts to the sweet life. She might be programmed to crank out too much of a "hunger" hormone, leptin, for example, and her overfed cells may be less sensitive than they should be to insulin, which normally enables cells to use glucose for energy. Both types of hormonal programming may leave her with a hearty appetite and tendency to overeat that are difficult to reverse. The Kaiser Permanente study found that even women whose blood sugar levels fell into the upper range of normal, 122 to 140 milligrams per deciliter, might benefit by lowering those levels further. Their children were almost 30 percent more apt to be fat by age 7 than those born to women with lower blood sugar levels. Women can move naturally into the safe zone by cutting back on sweets and processed starches like white bread, bagels, and pretzels, says study author Teresa Hillier, and by scheduling in 30 minutes daily of physical activity.
Hold the meat. Too much protein can apparently wreak havoc, too. In March, Scottish researchers released the findings from a study of 70 adult offspring of a group of women from a town in Scotland (appropriately named Motherwell) who were told in the 1960s to eat a pound of red meat a day during pregnancy to prevent high blood pressure. When asked to perform such challenging tasks as public speaking and mental arithmetic, these adults produced excessive amounts of the stress hormone cortisol, says Rebecca Reynolds, an endocrinologist at the University of Edinburgh who led the study. High cortisol producers tend to develop hypertension and carry fat around the abdomen, which increases the likelihood of heart disease and diabetes.