Pregnancy Weight Gain, Big Babies Linked
Gaining 40 Pounds or More Doubles Risk of Having a Big Baby, Which Increases Health Risks, Study Shows
Oct. 31, 2008 -- Gaining 40 pounds or more during pregnancy nearly doubles
the risk of having a baby who weighs 9 pounds or more, in turn increasing the
health risks to mother and baby, according to a new study.
Excessive pregnancy weight gain and big babies have often been linked, says
Teresa Hillier, MD, senior investigator at the Kaiser Permanente Center for
Health Research, Portland, Ore., and the study's lead author. Researchers have
also known that women who develop diabetes during pregnancy, called gestational
diabetes, are more likely to deliver heavier babies, Hillier tells WebMD.
But the new study is believed the first to conclude that women who gain
excessive weight during pregnancy are even more likely to have heavier babies
than women treated for gestational diabetes who don't gain excess weight.
"More than one in five women gain too much weight during pregnancy and
only 5% have gestational diabetes," Hillier tells WebMD. The study, she
says, points to the need for all women to follow recommendations about not
gaining excessive amounts of weight.
Pregnancy Weight Gain & Big Babies: Study Details
Hillier and her colleagues followed 41,540 women who gave birth to singleton
babies in Washington, Oregon, and Hawaii from 1995 through 2003. They used
patient medical records and birth certificates to note the mother's weight gain
and the baby's birth weight.
All mothers-to-be were screened for gestational diabetes.
The researchers analyzed the numbers of women who gained more than 40 pounds
-- the maximum recommended weight gain -- and whether their babies weighed more
than about 9 pounds at birth, which is considered a heavy baby.
Heavier babies are at risk of becoming heavy adults, Hillier says, and make
it more likely the mother will have to deliver by cesarean section, among other
increased health risks.
Pregnancy Weight Gain & Big Babies: Study Results
Overall, 12.5% of the babies -- or 5,182 -- were born weighing 8.8 pounds or
Overall, more than 20% of those who gained more than 40 pounds gave birth to
heavy babies, and less than 12% of those who gained less than 40 pounds had
Other results suggest that excess weight gain -- whether or not a woman has
gestational diabetes -- boosts the risk of having a heavy baby.
- While 16.5% of women with normal glucose who gained more than 40 pounds had
a heavy baby, only 9.3% of those who had normal glucose levels who gained less
than 40 pounds had a heavy baby.
- While 29.3% of women with gestational diabetes who gained more than 40
pounds had big babies, just 13.5% of those with gestational diabetes who gained
40 pounds or less did.
"Gestational diabetes puts the baby in an overfed state," Hillier
says. "When a mother gains too much weight, even if she has normal glucose
levels, the baby is overfed in a similar way."
Big babies are also more likely to get stuck during vaginal deliveries, she
says, and to be injured.