The offices of Dr. Mark Chames, an obstetrician at the University of Michigan Health System in Ann Arbor, are outfitted with some special equipment. The blood-pressure cuffs used on patients’ arms are actually thigh cuffs, originally designed to strap around a leg. Standard scales, which measure up to 350 pounds, have been supplemented by ones that accommodate 880 pounds. Before the new scales arrived, some patients were weighed at the hospital loading dock.
After
decades in which the obesity epidemic spread to every demographic
group in the nation, it has also ended up here: the maternity ward. One in five
women who give birth in the U.S. is obese, according to Susan Chu, an
epidemiologist at the Centers for Disease Control and Prevention.
And doctors are seeing more pregnant women who are morbidly obese, weighing
400, 500, even 600 pounds. Excess weight makes pregnancy riskier: obese women are more likely
to develop hypertension and diabetes, and to deliver prematurely. The need
to manage their conditions, and to meet their logistical needs, is giving rise
to a new medical subspecialty, what some are calling “bariatric obstetrics.”
Chames, who already sees at least a dozen morbidly obese pregnant women each
month, will direct his hospital’s new Center for Bariatric Obstetric Care when
it opens later this summer.
The challenges of caring for these patients begin early. “We perform an anatomical survey of the fetus, but in an extremely obese woman, the ultrasound signal often can’t penetrate through all the tissue,” Chames says. He must use a vaginal probe instead. A thorough examination is especially important in obese women, Chames said, because they are at greater risk of having babies with neural-tube defects and other malformations.
Birth brings more difficulties. The fetuses of obese women are often too large to fit through the birth canal; their mothers are about twice as likely as normal-weight women to need a Caesarean section. Longer surgical instruments are required, as are extra-wide operating-room tables, reinforced to support hundreds of additional pounds.
To head off such problems, patients at the bariatric obstetric clinic at St. Louis University in Missouri are counseled not to put on any pounds at all during pregnancy, and are even encouraged to lose weight. Dr. Raul Artal, the chairman of the ob-gyn department and the clinic’s director, acknowledges that the notion of weight loss during pregnancy can be startling. “It goes against everything we were taught in medical school, everything we’ve always told our patients,” he says. Some scientists warn that we still know little about the potential dangers of this approach. Emerging evidence, however, suggests that obese women who maintain or lose weight during pregnancy experience significantly fewer complications and deliver healthier babies.
In light of these findings, Artal and other obstetricians say the official recommendations on weight gain during pregnancy — which currently advise obese women to put on at least 15 pounds — need to change. The guidelines were issued by the Institute of Medicine in 1990, a time when low-birth-weight babies, not obesity, seemed the more pressing concern. In fact, a panel of experts has begun meeting to review the recommendations, not only for the obese but for all women. Their scrutiny comes at a time when studies show that many American women put on pounds in excess of the current guidelines and keep them on after they deliver. “Pregnancy,” Artal says, “is itself a major contributor to the obesity epidemic.”
It may contribute in still another way. New research suggests that the intrauterine environment provided by an obese woman makes it more likely that the fetus will grow up to be overweight later in life. A study of 1,044 mother-child pairs published last year in The American Journal of Obstetrics and Gynecology, for example, found that greater weight gain during pregnancy was associated with heavier children at age 3. Experiments with animals, in which variables can be strictly controlled, indicate that the mother’s body composition during pregnancy plays a role independent of genetic endowment or postbirth diet in predisposing offspring to obesity. The precise mechanism has yet to be established, but scientists theorize that the mother’s dietary intake, weight or circulating levels of nutrients and hormones sends a signal to the fetus, influencing its appetite control, metabolism and the way its genes are expressed.
If these theories are confirmed, we may come to view pregnancy not as a nine-month wait for the big event but as the crucible of a major health problem, obesity’s ground zero. “The reason this is so important is that the effects of excess weight during pregnancy reach into the next generation,” Susan Chu says. The maternity ward, in other words, is not just where obesity has ended up; it may be where it begins.