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The Expanding Role of AMH as a Predictor of Fertility

Erica Johnstone
Erica Johnstone, MD, MHS

While slowing down a woman's biological clock remains as futile as turning back time, reproductive medicine is finding a way to peer inside the clock to gauge just how fast it is ticking.

One such clue is a test measuring anti-Müllerian hormone (AMH) concentrations, reflecting the activity of the ovaries during a woman's lifetime and estimating her remaining egg supply. Where a woman falls on this fertility scale may help her learn the likelihood of becoming pregnant now and how that might change in the foreseeable future.

This is knowledge in demand considering one-third of the approximately 20 percent of women who have children after 35 will experience fertility issues, according to the Centers for Disease Control and Prevention. For example, when levels of AMH fall below a certain level, the infertility treatment in vitro fertilization (IVF) becomes less successful.

"AMH testing can be helpful for women who are 35 and older and determining their fertility options," says Erica Johnstone, MD, MHS, a University of Utah fertility and reproductive endocrinologist. "Is the window rapidly closing or is there more time?"

Sometimes described as the new "egg timer," AMH levels may provide women with a sense of how long their fertility might last. "AMH gives us information about a woman's ovarian reserve "bank"—how many eggs she has left at that particular point,'" explains AMH researcher Joely Straseski, PhD, medical director of Endocrinology at ARUP Laboratories. Fewer eggs mean fewer chances for conceiving a baby.

"There isn't a specific level of AMH that will let you know whether you will or won't get pregnant, but it can show you whether your ovaries are aging more quickly or more slowly than average," says Johnstone, emphasizing it provides insight into the quantity not the quality of the eggs. Currently, age is the strongest predictor in estimating egg quality.

While an antral follicle count (AFC), via a transvaginal ultrasound, is the gold standard for determining a women's egg count, AMH concentrations correlate with AFC better than any other currently available options. AMH testing has been around for more than five years, but the sensitivity of the test has progressively become more honed. Last year, ARUP Laboratories implemented a new ultra-sensitive test that is more than 20 times more sensitive than any other AMH test available.

Women who are having trouble getting pregnant may have their AMH levels tested and then be referred to a fertility specialist. Or, women who are opting for IVF may be tested so their specialist can better tailor hormone treatment to optimize the success of the procedure. "With the cost and emotions involved in IVF treatments, you really want to be as accurate as possible in prepping a woman's body for implantation," stresses Straseski.