Why the health of pregnant women matters to us all
"Pregnant Is the New Sexy," read the T-shirt a friend gave me when I was a few weeks away from my due date. With my swollen ankles and waddling walk, I wasn't so sure - but it's hard to deny that pregnancy has become rather chic. Glossy magazines flaunt actresses' and models' rounded, half-clad bellies on their covers. Inside they chronicle celebrities' pregnancies in breathless detail, from the first "bump" sighting to the second-trimester weight gain to the baby-gear shopping spree. And now comes the news that "What to Expect When You're Expecting" - the advice bible that has sold more than 14 million copies - will be made into a feature film.
There's something wrong with this picture. Even as Americans fuel a rapidly growing pregnancy industry of designer maternity jeans and artsy pregnancy portraits, we're ignoring the real news about these nine months. An emerging science known as the developmental origins of health and disease - DOHaD for short - is revealing that the conditions we encounter in the womb can have a lifelong impact on our health and well-being, affecting everything from our appetite and metabolism to our susceptibility to disease to our intelligence and temperament.
The more we learn about these effects, the clearer it becomes that investing in maternal health would return larger and longer-lasting dividends than almost any other comparable public health investment. But as a nation, we're heading in exactly the opposite direction, spending more and more of our limited resources on the later stages of life instead of where they can make the most difference: at the very beginning.
Take obesity. Many anti-obesity initiatives concentrate on changing adults' behavior, trying to persuade us to eat less and exercise more. But research shows that these efforts have limited effectiveness. A recent analysis of U.S. obesity-prevention campaigns, conducted by Olaf Werder of the University of New Mexico, concluded that their "overall impact on obesity has been negligible."
Even public health programs aimed at school-age children come too late: Almost a third of American children over age 2are already overweight or obese, according to the National Health and Nutrition Examination Survey. Clearly, the conditions that contribute to obesity must begin exerting their influence very early in children's lives - as early as their time in the womb.
DOHaD research shows that the intrauterine environment of a woman who is significantly overweight when she conceives - or who puts on excessive weight during pregnancy - affects the developing fetus in ways that make it more likely to become overweight itself one day. Scientists are still figuring out exactly why this happens, but it appears that prenatal experience may alter the functioning of organs such as the heart and the pancreas, may shift the proportion of lean and fat body mass, and may influence the brain circuits that regulate appetite and metabolism.
In a cleverly designed study published in the Journal of Clinical Endocrinology and Metabolism in 2009, researchers compared children born to the same mothers before and after they'd had successful anti-obesity surgery. Children born after their mothers' surgery weighed less at birth and were three times less likely to become severely obese than their older brothers and sisters. Weight-loss surgery isn't for everyone, of course. Still, what if before conceiving, overweight women were routinely counseled by their doctors about the effects of their weight on future offspring? And what if women who were gaining weight too rapidly in pregnancy were offered more help in controlling it?
The results might look something like those found in studies of diabetes treatment during pregnancy. Research shows that the children of diabetic women are more likely than others to develop diabetes - in one recent study, seven times more likely. Like obesity, diabetes has a strong genetic component, but scientists are also beginning to focus on the effects of a diabetic intrauterine environment. For example, a long-running study of the Pima Indians of Arizona, who have one of the highest rates of diabetes in the world, concluded that exposure to the disease while in the womb was responsible for about 40 percent of the diabetes cases studied.
A pregnant woman's diabetes can also affect the odds that her child will become obese. In a study of almost 10,000 mother-child pairs, researchers from the Center for Health Research at Kaiser Permanente Northwest found that women who developed diabetes during pregnancy and were not treated had children who were twice as likely to become obese as the children of women without that illness. Pregnant women whose diabetes was treated with insulin, however, had children with no additional risk of obesity. Simply by controlling their mothers' blood sugar during pregnancy, in other words, the expected doubling of these children's obesity risk was completely reversed.
Even the mental health of a pregnant woman can have a long-term impact on her offspring. A 2008 study by researchers at the Kaiser Permanente Oakland Medical Center in California found that women with even mild symptoms of depression are 60 percent more likely to deliver early than other women; those who are severely depressed have double the risk of premature birth. The babies of depressed women are also more likely to have low birth weight, to be irritable and to have trouble sleeping.
Of course, these complications may come about in part because many depressed women don't take good care of themselves: They may eat poorly, smoke or drink alcohol, or fail to get prenatal care. But depression itself may shift the biochemical balance in a woman's body in a fateful manner. For one thing, the stress hormone cortisol, which is often elevated in people with depression, may cross the placenta, directly affecting fetal development, and it may also affect a pregnant woman's blood vessels, reducing the oxygen and nutrients that reach the fetus.