For decades after a woman has carried a male child in her womb or shared her mother's womb with a brother, she carries a faint but unmistakable echo of that intimate bond: male fetal DNA that lodges itself in the far recesses of her brain.

That astonishing finding, publishedWednesday in the journal Public Library of Science One (PLoS One), suggests that the act of having a child is no mere one-way transmission of genetic material and all that goes with it: There is an exchange of DNA that passes into the part of us that makes us who we are. That, in turn, may alter a woman's health prospects...

When a doctor warns a potentially dangerous driver to stay off the roads, it cuts the risk that the driver will crash a motor vehicle and wind up in an emergency room, Canadian researchers reported Wednesday.

In a study published in the New England Journal of Medicine, the team looked through patient data from drivers in Ontario who were older than 18 and had a valid national health card number and found that 100,075 had received warnings not to drive from 6,098 doctors between April 1, 2006, and Dec. 31, 2009.  The "typical patient," the authors wrote, was a 60-year-old man who lived in a city...

There’s a lot of talk these days about the role of gut bacteria in disease and health. The latest report in that area: a study in Nature that finds differences between the bacteria growing in the guts of people who have diabetes and those who don't.

The Chinese and European authors of the study used DNA analysis to figure out the bacterial populations inside 345 Chinese people.

They found that people with diabetes had mild gut disturbances. They had fewer bacteria that make a compound called butyrate, for example. And they had higher levels of various bacteria that can increase in number...

Celebrities often endorse health causes -- think Michael J. Fox and Parkinson's disease, Montel Williams and multiple sclerosis, Rosie O'Donnell and desmoid tumors.

Then think Jenny McCarthy and autism -- and her conviction that it is caused by childhood vaccines.

Clearly, celebrity endorsements are a double-edged sword.

This week's edition of the British Medical Journal poses the question "Does celebrity involvement in public health campaigns deliver long-term benefit?” and offers up two very different opinions.

Coming down on the "yes" side is Simon Chapman, professor of public health at...

The epidemic of obesity in childhood — a condition that has tripled in recent decades and now affects some 12.5-million American kids — appears likely to put an entire generation at high risk of heart disease, says a new study. But just as scientists have had difficulty predicting how climate change would play out, they know little of how, exactly, a generation of obese kids will be affected in adulthood by their childhood weight, says an accompanying editorial.

Published in the British Medical Journal, a comprehensive reviewof 63 existing studies — known as a meta-analysis...

A new study suggests that a physician's gut feelings -- a sense that something is wrong even when everything checks out in the standard clinical exam -- may contain more information than he or she gives them credit for.

A growing literature has begun to ask whether such gut feelings add anything substantive to a doctor's clinical exam. But in general the studies have been limited by a shaky understanding of just what is meant by gut feeling -- specifically, which aspects of a patient visit lead to a doctor’s gut feeling that are not part of the standard clinical exam.

The authors of the...

But some doctors do have concerns about the legislation, which also requires physicians to tell patients that dense breasts are linked to a higher risk of breast cancer, that they make mammograms harder to read and that there are alternative breast cancer screening options.

Here are the thoughts of three doctors with whom we spoke. (Also see our blog item on this topic from yesterday.)

Dr. Otis Brawley, chief medical and scientific...

Packaged foods can be hard – not to cook, necessarily, but to choose. Deciphering the many labels can be confusing, with nutritional information, claims such as “reduced fat” and advertising perhaps blending together among the many products on a shelf.

Researchers in this country and others have been working to find a system of icons to put on the front of packages to help shoppers sort through the cacophony to figure out which products are healthful. In a new study published Tuesday in the journal Preventing Chronic Disease, researchers – from Yale and Cornell...

Are you free on Nov.1? We’ve got just the thing for you! We learn from our morning mail that for $99 you can check out a “Snacking in America Webinar” put on by the Food Institute, a trade group. It notes that “Eating patterns are evolving in the U.S. and SNACKING has become the hottest trend!"

No kidding. May have something to do with why we’re becoming so ... lardy.

At the one-hour webinar, food industry participants can:

— “Uncover long-term trends in snacking behaviors and snacking choices.”

— "Explore the relationship between snacking &...

Did an aggressive anti-smoking campaign conducted earlier this year influence people to give up smoking? There's a good chance the $54-million campaign by the Centers for Disease Control and Prevention did have an effect, an article in the Annals of Internal Medicine reports.

But it was short -- just three months long. And the impressive-sounding $54 million pales in comparison to the $27 million spent every day by the tobacco industry for marketing, the authors wrote.

Nancy Rigotti and Melanie Wakefield described the campaignin the Annals of Internal Medicine, as well as what's known about...

The Summer London Olympics may have inspired the bouncier among its viewers to take to the trampoline, but parents should not allow its use at home, the American Academy of Pediatrics says.

In an article Monday in the journal Pediatrics, the pediatricians group “strongly discouraged” the use of home trampolines. The academy updated previous, similar statements because of the growth of trampoline as a competitive sport and the popularity of indoor trampoline parks.

Injury rates at those parks are unknown but should be monitored, the journal article says. The academy did not oppose...