NEW YORK (Reuters Health) -
Babies born to overweight or
obese women have more fat and less muscle than infants born to
normal-weight moms, according to one of the first studies to
compare newborns' body composition to their mothers'
pre-pregnancy body mass index (BMI).

Obesity is on the rise among pregnant women, while more and
more North American and European infants weigh 4,000 grams (8
pounds 13 ounces) or more at birth, Dr. David A. Fields of the
University of Oklahoma Health Sciences Center in Oklahoma and
colleagues Fields and his team note in their report in American
Journal of Obstetrics & Gynecology. These unusually heavy
infants are more likely to grow up to be obese.

Body weight alone, however, doesn't provide a clear picture
of infant growth and health, the researchers add; both low and
high birth weight have been tied to an increased risk of
diabetes and other conditions in adulthood.

To better understand how prenatal growth might influence
future health, Fields and his team used the PEA POD, a “body
composition system” made by Concord, California-based Life
Measurement Instruments, to measure the percentage of body fat,
fat-free body mass, and total fat mass in 72 babies no older
than 35 days.

There was no difference in average birthweight between
babies born to women with normal BMIs and those whose mothers
were overweight or obese.

However, infants of the 39 overweight or obese moms had
significantly higher percentages of body fat (13.6 vs. 12.5
percent), higher fat mass (448.3 grams vs. 414.1 grams), and
lower fat-free mass (3,162.2 grams vs. 3,310.5 grams) than the
babies born to the 33 normal-weight women, Fields and his team
found.

Babies born to heavy mothers may face a greater risk of
diabetes because they have less muscle mass, Fields noted in an
interview. “That could be reason why these kids, probably many
of them, will get diabetes, because muscle is your largest
consumer of sugar,” he said.

“It's been very, very difficult to measure the body fat in
the baby,” Fields noted. Previously, doing so required using
several different machines and took hours. The PEA POD can
gauge body composition in five minutes, according to Life
Measurement Instruments' Web site.

The machine is expensive, Fields noted, estimating that
just 15 are in use worldwide. Nevertheless, he predicted that
more and more hospitals will begin using them.

Gauging babies' body composition at birth could provide a
clearer picture of their health than weight alone, Fields
added, but then the question remains as to what should be done
if babies are found to have a high percentage of body fat. One
possibility, Fields said, would be to encourage their mothers
to breastfeed. His own research has demonstrated that
formula-fed babies tend to be fatter.

SOURCE: American Journal of Obstetrics & Gynecology, April
2008.