ó A Drexel University study suggests that obesity is the
single most important characteristic that increases a pregnant
womanís chance of having a rare and heartbreaking occurrence
obesity is a known risk factor for fetal death, as well as for
pregnancy complications such as gestational diabetes.
current obesity epidemic is intensifying concern, and
prompting updated analyses of the stillbirth risk.
while rare, do routinely occur in all institutions serving the
Philadelphia area," said study leader Ruofan Yao, an
obstetrics-gynecology resident at Hahnemann University
Hospital. "The major motivation for this study was to
contribute to existing knowledge to identify at-risk
about three out of every 1,000 pregnancies of 28 weeks or more
ended in stillbirth, and the rate has been inching down for
decades, according to federal data.
how obesity impacted this risk, Yao and colleagues used
records from Texas and Washington, which are among 17 states
that collect pre-pregnancy weight data along with birth
analysis found 9,030 stillbirths among 2.8 million
single-child deliveries between 2003 and 2011.
half of the women in the analysis were of normal weight; 26
percent were overweight; and the rest fell into four
increasingly severe categories of obesity. Nearly 4 percent
were morbidly obese, with a Body Mass Index (a ratio of height
to weight) of 40 or more ó or at least 235 pounds for a
5-foot, 4-inch woman.
the researchers found the stillbirth rate mirrored the
national one ó three in 1,000 births. But as the motherís
weight and the fetal age increased, so did the risk of
stillbirth. It doubled for moderately obese women, more than
doubled with morbid obesity, and tripled with
"super" obesity (a BMI of 50 or more).
term ó between 37 and 42 weeks ó the stillbirth risk for
the most obese women skyrocketed. At 41 weeks, for example, a
super-obese woman was almost 14 times more likely to have a
stillbirth than a normal-weight woman. Thatís a more
powerful link than previous studies have found.
donít think anybody expected to see so much increase in
risk," Yao said.
obesity was associated with a quarter of the stillbirths that
occurred at term, which "would make obesity the single
most important risk factor Ö in the general
population," the researchers wrote.
why maternal fatness is harmful to the fetus is unclear, but
it may involve insufficient oxygen, or hormonal or metabolic
disturbances. Yao and his colleagues speculate that
deterioration of the uterus or placenta plays a role.
Drexel, he said, "we perform more routine ultrasounds and
monitor fetal growth," and recommend delivery on the due
date if an obese woman doesnít go into labor beforehand.
there is no evidence that fetal surveillance reduces
stillbirth, the researchers say in their study, published
online last month in the American Journal of Obstetrics and
women to lose weight before becoming pregnant is another
preconception counseling part ó we can probably do
better," Yao said. "There are a lot of things women
can do before pregnancy to reduce their risk. Unfortunately,
thatís not always part of the conversation."