The original idea that pregnancy was dangerous for such women came not from medical research, as most scientists think, but from a decision made by a high-ranking official in Nazi Germany's eugenics program to remove people with genetic defects from the population, said Dr. William H. Lippy, an Ohio physician in private practice who conducted the study.

The key to disproving the link came from his observations of devout Jewish women in Israel, Lippy reported this week at a meeting of the Triological Society, an organization of ear, nose and throat doctors.

The tale is a lesson in how information that "everybody knows to be true" is handed down from one generation of physicians to the next without question, Lippy said. "What I practiced all these years, what many of my colleagues practiced, was wrong."

"This is good information, better than what we have ever had," said Dr. Brad Welling of Ohio State University. "In terms of family planning, however, it is not going to make a lot of difference."

Treatment for otosclerosis is now so successful, he said, that most women with the disorder can feel free to have children whether the pregnancy exacerbates their hearing loss or not.

Dr. Rick A. Friedman of the House Ear Institute in Los Angeles, however, said his own experience over the years made him skeptical of Lippy's findings.

"Each of us has gotten histories from women in which they noted onset of hearing loss during pregnancy or exacerbation," he said. "I still think there is some association."

Otosclerosis is a problem with the stapes, one of the three bones of the inner ear -- commonly known as the hammer, anvil and stirrup. These bones carry sound vibrations from the ear drum to the inner ear.

In otosclerosis, for reasons that are still unknown but that may be primarily genetic, the third bone in the series, the stapes or stirrup, becomes fixed in the inner ear. It is almost like the bone is cemented into place, preventing it from conducting sound efficiently.

The condition affects an estimated 500,000 Americans, two-thirds of them women. It once meant a life of deafness, but it can now be ameliorated with hearing aids or, in more severe cases, with a stapedectomy, a brief procedure in which an artificial stapes is implanted in the ear.

By Thomas H. Maugh II, Los Angeles Times