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Obesity
Before Pregnancy Ups Risk of Birth Defects
Women who are obese when they become pregnant appear to
be more likely to give birth to babies with various birth
defects than women of healthy weight, new research suggests.
Moreover, simply being overweight but not obese at the time
of conception seems to increase the risk of having a child
with heart defects or more than one unrelated birth defect.
Previous research showed that women who are obese before
becoming pregnant have a higher-than-average risk of giving
birth to a baby with defects in the brain and spinal cord,
and the current findings extend that risk to other types
of defects.
During the current study, a team led by Margaret L. Watkins
at the Centers for Disease Control and Prevention in Atlanta,
Georgia, interviewed mothers of more than 600 babies born
with certain birth defects between 1993 and 1997 and compared
their responses to those of 330 mothers of babies who did
not have those birth defects.
The researchers determined whether a woman carried excess
body weight before giving birth by asking her height and
weight before she became pregnant, then using that information
to calculate her body mass index (BMI).
The authors found that women who were obese before pregnancy
were more than three times as likely as women of average
weight to have children with spina bifida, a defect in which
one or more of the vertebrae fails to develop completely,
leaving a portion of the spine exposed.
Obese women were also twice as likely to have a child with
heart defects and more than three times as likely to give
birth to a baby with a defect in the abdominal wall known
as omphalocele, the authors report in the journal Pediatrics.
Relative to women of healthy weight, women who were overweight
but not obese had around a two-fold higher risk of having
infants with either heart defects or more than one unrelated
birth defect.
The reasons why excess weight in the mother can increase
the risk of birth defects is unclear, Watkins told Reuters
Health.
She suggested that overweight and obese women may have certain
metabolic abnormalities that could affect the growth of
cells in a developing embryo. Alternatively, overweight
and obese mothers may have undiagnosed diabetes, a condition
that has been shown to increase the risk of birth defects.
Although she and her colleagues relied on women's memories
of their height and weight before becoming pregnant -- a
notoriously unreliable strategy -- Watkins said that people
typically overestimate their height and underestimate their
weight.
"If anything, what we've got here probably underestimates
a person's BMI," she said. "I don't think we're
overstating the risk, for that reason."
Watkins added that it may be a good idea to get the message
out early to women -- even before they are ready to conceive
-- that their weight can place their unborn child at risk.
Overweight children tend to become overweight adults, she
said, and targeting anti-obesity efforts to children may
have a significant impact on the number of women who enter
their reproductive years already carrying excess weight.
"I really think this is a problem that needs to be
approached early in life, and not just at reproductive age,"
she noted.
SOURCE: Pediatrics 2003;111:1152-1158.
Article Source: Reuters Health
Article Author: Alison McCook
Net Reference 89
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