Rapid Weight Gain May Put Boys at Risk

Feb. 10, 2003 -- Boys who are born thin but gain a lot of weight as adolescents may be more likely to develop high blood pressure than others. A new study shows that boys who were thinnest at birth and gained the most later on had the highest risk of having high blood pressure.

Low birth weight among full-term infants might be a sign of growth retardation in the womb, the researchers say, which could increase the long-term risk of chronic diseases.

The researchers say their findings are in line with a theory known as fetal programming or the Barker hypothesis, which states that a malnourished fetus will adapt its metabolism in the womb to survive until birth, but these changes then increase a person's risk of disease later in life, such as heart disease, diabetes and possibly cancer.

Prior studies have already shown that children who are thin at birth and are heavy as adolescents are at increased risk for heart disease, but until now it wasn't clear if particular growth periods played a role.

Researchers say the results demonstrate the need for pregnant women to get adequate nutrition and prenatal healthcare to help ensure their babies are born at a healthy weight.

In the study, researchers tracked the growth rates of more than 2,000 Filipino boys and girls through ages 14 to 16 and compared them with high blood pressure rates.

The results appear in the February issue of Hypertension: Journal of the American Heart Association.

"The boys who were thinnest at birth and who gained the most weight during childhood and adolescence were the ones who had the greatest risk of high blood pressure," says researcher Linda S. Adair, PhD, professor of nutrition at the University of North Carolina at Chapel Hill, in a news release.

No such association was found for girls in the study. Although girls who had a large weight gain between ages 8 and 15 were more likely to have elevated blood pressure, this risk was not related to birth weight.

In addition, the increased risk associated with rapid weight gain during adolescence was found only among boys who were thin at birth. Rapid growth during infancy did not seem to have an impact.

"Faster growth in infancy did not represent a risk for increased blood pressure in adolescence for either sex," says Adair. "This period of weight gain may even be slightly protective against high blood pressure later. This is an important finding because pediatricians want to see improved growth in babies born small."