Unborn babies lose out in a competition for nutrients with their young — and still growing — teen mothers, leading to future health problems for both, a recent study reveals.

There is a link between maternal growth, obesity and low birth-weight babies in a large percentage of pregnancies that occur while the mother-to-be is still growing, according to Dr. Theresa Scholl, professor of epidemiology in obstetrics and gynecology at the University of Medicine and Dentistry of New Jersey.

Scholl shared results of her research on pregnant teenagers in Camden, N.J., during a Philadelphia-based panel discussion exploring maternal and child nutrition.

It is normal for mature women — those 19 and older — to "shrink" slightly during pregnancy as nutrients flow to the fetus, Scholl explained. However, approximately half of teenage pregnant women grow during the gestational period. The metabolic shift that needs to take place to establish the proper balance of nutrients to the mother and to the fetus fails to take place in teenagers who are still growing when they become pregnant, she said.

This "glitch" negatively affects the mother and the fetus, Scholl continued. The mother deposits and retains more fat than normal during pregnancy, leading to abnormal weight gain, postpartum retention of weight and future obesity.

In addition, the fetus, in competition with the mother for fuel, is denied sufficient nutrition, resulting in a low birth-weight and related health defects, she said, noting that the "metabolic demands of the young mother take precedence over the nutrient demands for fetal growth." When these growing teenagers attempt to restrict caloric intake, they transmit less iron and folic acid to the fetus, adding to the risk of low birth-weight already increased by the mother's growth, Scholl said.

When asked about possibilities for preventing this phenomenon in teenage pregnancies, Scholl suggested reducing the mother's insulin production. Eating more frequent, small meals could be one way to achieve this effect, she said.