How Fast Is Your Biological Clock Ticking?

Aug. 9, 2011 -- Science may soon be able to predict more accurately how long a woman will remain fertile. A survey of healthy women carried out at the University of St. Andrews and by experts from both the University of Edinburgh and University of Glasgow, all in the U.K., has revealed the normal range of levels of a hormone considered vital to a woman's fertility.

The findings are likely to help younger women find out whether they can expect to have an early or later menopause and thus how long they may be fertile.

AMH Hormone Levels

The survey showed the normal range of levels of the anti-Mullerian hormone (AMH) in relation to age. This hormone reflects the activity of the ovaries during a woman's lifetime and gives an estimate of her remaining egg supply.

The study looked at 3,200 samples from healthy girls and women to find out the average levels of AMH. The findings will now allow fertility experts to tell how a women's AMH level compares with the average for her age.

Tom Kelsey, a lecturer in the School of Computer Science at St. Andrews, says, "We knew that high AMH levels were good for conception, but we could not back that up statistically. This study now provides us with the level you would expect to find in a normal, healthy woman."

Implications for IVF

It is already known that when levels of AMH fall below a certain level, the infertility treatment in vitro fertilization (IVF) becomes less successful. By offering a benchmark, the new findings could help give a more accurate prediction of a successful outcome from IVF.

Assessment of AMH is already being used widely in IVF treatment, says Richard Anderson, professor of reproductive medicine at the University of Edinburgh. "Predicting how long you might remain fertile is very important, and it seems that AMH can help in this. Our data show how AMH changes with age in normal women."

Counseling

Professor Hamish Wallace, pediatric oncologist at the Royal Hospital for Sick Children in Edinburgh, says, "Currently there is no accepted test that will reliably predict how many immature eggs remain for an individual girl or young woman. For a young patient with cancer who may be at high risk of infertility as a result of their proposed treatment, our study will assist the counseling of these vulnerable patients at diagnosis and may influence decisions on fertility preservation before they start their cancer treatment."

Professor Scott Nelson of the University of Glasgow's School of Medicine says, “We can now interpret a woman's or child's AMH with confidence, and that is a huge step in ensuring we can counsel patients regarding their potential reproductive life span."

It is hoped that the results of this survey will help in the development of tests to predict a woman's potential reproductive life span. Blood tests are used at present to measure AMH levels. Researchers are investigating how levels of this hormone may be determined in urine.