Starting The Good Life In The Womb

Most pregnant women know they can hurt their babies by smoking, drinking alcohol and taking drugs that can cause birth defects. But they also may be able to "program" the baby in the womb to be a healthier adult. New research suggests that mothers-to-be can reduce the risk that their babies will develop obesity, high blood pressure, heart disease and diabetes by monitoring their own diet, exercise and weight.

The science behind this is relatively new and still somewhat controversial. In the late 1980s, a British physician and epidemiologist named David Barker noticed that a group of Englishmen who were born small had a higher incidence of heart disease. Studies showed that rates of obesity, high blood pressure and diabetes—illnesses that often are associated with heart disease—are higher in men born small. Barker proposed that poor nutrition in the womb may have "programmed" the men to develop illness 50 years or more later.

The "Barker Hypothesis" is still hotly debated, but it is gaining acceptance as the evidence builds. Because organs develop at different times, it appears that the effects of too little food during pregnancy vary by trimester. One example comes from study of the Dutch Hunger Winter, a brief but severe famine that occurred during World War II. Pregnant women who didn't get enough to eat in their first trimester had babies who were more likely to develop heart disease. If they were in their second trimester, their babies were at risk for kidney disease. A poor diet in the last three months led to babies who had problems with insulin regulation, a precursor of diabetes.

More-recent research has focused on the negative effects of too much food during pregnancy. Women who gain excessive weight during pregnancy are more likely to have babies who are born large for their age and who become overweight in childhood. A recent study from the National Birth Defect Prevention Study found that obesity in pregnancy also increases a baby's risk for birth defects, including those of the spinal cord, heart and limbs.

A mother's nutrition and exercise patterns during pregnancy influence the long-term health of the baby by shaping her baby's metabolism. "Metabolism" includes everything that allows your body to turn food into energy—from the organ systems that process food and waste to the energy-producing chemical reactions that take place inside every cell. It is the collective engine that keeps you alive.

A mother's body may influence her baby's metabolism on many levels: the way organs develop, how appetite signals get released in the brain, how genes are activated, even the metabolic chemistry inside the baby's cells. Research now shows that the environment of the womb helps determine how a baby's metabolism is put together, or "programs" it for later health. The science of fetal programming is still new; it will be a long time before we have all the answers, since these health effects emerge over a lifetime. But several principles already are clear for a pregnant woman.