Eating for two could be bad advice

More than 60 percent of U.S. women of childbearing age are overweight or obese -- a significant increase from 20 years ago. And recent studies strongly suggest either too much or too little nutrition in utero can increase a fetus' chance of becoming an overweight child and overweight adult.

Such data on the increasing girth of pregnant women and the growing rates of obesity in children led to pressure on the Institute of Medicine to revise a set of 1990 guidelines that were written primarily to prevent the birth of excessively small infants. Numerous medical journal articles in recent years have called the guidelines irrelevant to today's obstetrics patients.

On Thursday, the institute's advisory committee made up of doctors and researchers issued the updated recommendations. But with the exception of a few areas, such as putting a limit on how much weight obese women should gain, the new guidelines are the old guidelines wrapped up in a lecture.

The panel said the existing guidelines are essentially fine. It's women and their doctors, the members said, who need to try harder -- often much harder -- to reach a normal weight before pregnancy and to avoid excessive weight gain during pregnancy.

"Although not dramatically different, fully implementing the guidelines will represent a change in the care provided to women of childbearing age," said Kathleen Rasmussen, chairwoman of the committee and a professor of nutrition at Cornell University. "If [the guidelines] look the same, that tells me these are a pretty robust set of recommendations. That should give doctors confidence that these are the recommendations they should be following."

The report was requested by six major health organizations so doctors could better advise their patients.

But several leading experts on maternal obesity and child health expressed disappointment with the document. A growing contingent of doctors say obese women need to gain little or no weight during pregnancy. "In my opinion, the Institute of Medicine is missing an opportunity to address the issue of the obesity epidemic and the contribution that pregnancy makes to that epidemic," said Dr. Raul Artal, chairman of the department of obstetrics, gynecology and women's health at Saint Louis University.

"It's really a teachable moment," said guidelines co-author Dr. Patrick Catalano, obstetrics chairman at Ohio's Case Western Reserve University. "When women are pregnant, they may be more accepting" of weight discussions "because it's also in the best interest of their babies."

The guidelines' only change is for obese women, who were previously advised to gain at least 15 pounds, with no upper limit. They're now told to gain 11 to 20 pounds.

The weight categories are defined by body mass index. In another change, the committee opted to use BMI definitions used by the World Health Organization instead of a currently used BMI table from the Metropolitan Life Insurance Co. The WHO guidelines classify more women as overweight and fewer as obese.

What if a mom-to-be has gained too much? On average, overweight and obese women already are gaining five more pounds than the upper limit.

But pregnancy is not a time to lose weight, said guidelines co-author Dr. Anna Maria Siega-Riz of the University of North Carolina, Chapel Hill.

"It's not, 'Hey you gained enough, now you need to stop,'" Siega-Riz said. "Let's take stock of where you're at and start gaining correctly."

There's a zoo full of critters living on your skin -- a bacterial zoo, that is.

Healthy skin is home to a much wider variety of bacteria than scientists ever knew, says the first big census of our co-inhabitants. And that's not a bad thing, said genetics specialist Julia Segre of the National Institutes of Health, who led the research.

Sure they make your sneakers stinky, "but they also keep your skin moist and make sure if you get a wound that [dangerous] bacteria don't enter your bloodstream," she said. "We take a lot for granted in terms of how much they contribute to our health."

People's bodies are ecosystems, believed home to trillions of bacteria, fungi and other microbes that naturally coexist in the skin, the digestive tract and other spots. But scientists don't have a good grasp of which microbes live where, much less which are helpful, even indispensable, in maintaining health. The NIH's "Human Microbiome Project" aims to change that.

The skin research, in today's edition of the journal Science, is part of that project. Scientists decoded the genes of 112,000 bacteria in samples taken from a mere 20 spots on the skin of 10 people. Those numbers translated into roughly 1,000 strains, or species, of bacteria.

Topography matters, a lot. If a moist, hairy underarm is like a rain forest, the dry inside of the forearm is a desert. They harbor distinctly different bacteria suited to those distinctly different environments. In fact, the bacteria under two unrelated people's underarms are more similar than the bacteria that lives on one person's underarm and forearm.

The Associated Press contributed to this report.