For many women, a birth control pill that eliminates monthly menstruation might seem a welcome milestone.

But others view their periods as fundamental symbols of fertility and health, researchers have found. Rather than loathing their periods, women evidently carry on complex love-hate relationships with them.

This ambivalence is one reason that a decision expected next month by the Food and Drug Administration has engendered controversy. The agency is expected to approve the first contraceptive pill that is designed to eliminate periods as long as a woman takes it. Doctors say they know of no extra risk to the new regimen, but some women are uneasy about the idea.

“My concern is that the menstrual cycle is an outward sign of something that’s going on hormonally in the body,” said Christine L. Hitchcock, a researcher at the University of British Columbia. Ms. Hitchcock said she worries about “the idea that you can turn your body on and off like a tap.”