Biological Alarm Clock

Nancy Caspell thinks she can have it all. At age 28, she isn't ready for children. Even though she's not in a serious relationship, she figures by the time she hits age 35 or 40 she'll have met the man of her dreams, be more established in her career and, as with all happy endings, finally be ready for pregnancies and kids.

She only hopes her ovaries agree.

"I don't want to be one of those women who find out too late that my eggs are fried and the only thing I have to look forward to is wrinkles," says Caspell, a sales rep from Cleveland. "But I think my biological clock will keep ticking for a while."

With any luck it will. But it may not be ticking as long as Caspell hopes. Too many women, say doctors, assume their biological clock will run full-tilt well into their 40s. And despite medical advances in women's health, there is still no good early-warning test to determine exactly when a woman will go through menopause and her biological clock will run out. Most women go through menopause between the ages of 45 and 55, but it can happen anytime between 40 and 60. That's a big span. And for women who may be destined to go through menopause on the early side, finding out that they're not as fertile as they thought they'd be in their late 30s can be a heartbreaking surprise.

But now researchers in the Netherlands think they may have found a way to give women more warning—and it has nothing to do with age, but rather with an ovarian hormone called AMH. In a study to be published in the June issue of the Journal of Clinical Endocrinology & Metabolism, researchers from the University Medical Center Utrecht say that anti-Mullerian hormone, or AMH, is actually a better predictor of a woman's reproductive age than chronological age. AMH is a marker of what doctors call ovarian reserve, which is related to the quality and number of eggs in the ovaries and how well the ovarian follicles, tiny sacs in which eggs mature, respond to hormones.

In their study the researchers looked at the AMH levels in a group of 144 healthy, fertile women ages 25 to 46. Using that information and the results of a reproductive history survey of older women between 50 and 70, they created a data model that can predict, they say, when a woman will go through menopause within a few years.