Scientists can see time left on biological clock

A NEW method that may help women to beat the biological clock by predicting how long they have left to have a baby has been discovered by Scottish researchers.

For the first time, a team from St Andrews, Glasgow and Edinburgh has found how levels of a hormone, which can reveal how many eggs a woman has remaining, change throughout her reproductive life.

The discovery will allow women to compare their own hormone levels with the average for their age to see whether they should be concerned about their future fertility.

This will indicate whether they are likely to have an early or later menopause, meaning they know whether they have to try for a baby sooner rather than later. It will also help young women who have had treatment for diseases such as cancer, which may have affected their fertility, to find out whether their hormone levels have been affected.

Gauging female fertility has become more important, as more women are choosing to have children later even though their reproductive lifespan is limited. Figures show that the average age of mothers in Scotland has increased from 27.4 in 1991 to 29.6 in 2010.

The number of women giving birth aged between 35 and 39 has risen from 6,577 in 1998 to 9,448 in 2009, while those over 40 rose from 981 to 2,006 over the same period.

But this trend has raised concerns that some will struggle to conceive if they delay motherhood for too long, leading to a search for ways of predicting when women should attempt to conceive.

For the latest research, the Scottish researchers gathered together all previous data plus their own new findings on the Anti-Mllerian Hormone (AMH) - a hormone produced by growing, egg-producing ovarian follicles.

The researchers set out to map how levels of AMH vary at different points in the lives of healthy women by studying data from 3,200 women. As a result, they were able to deduce how a woman's AMH level compares with the average for her age.

This could indicate whether they are likely to have an earlier menopause and should not delay trying to conceive, or whether their fertile life will end later.

The study found that AMH levels peaked at the age of 24 but had almost halved by the time women were in their mid-30s and were almost nonexistent by their late 40s. Tom Kelsey, a lecturer in the School of Computer Science at St Andrews, said: "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."

Professor Scott Nelson, from the University of Glasgow, said a major use of the new findings could be in helping young cancer patients wondering how their treatment may have affected their chances of having a baby."We can now see 18-year-old girls, know what their AMH is and put that into context," he said.

Nelson added that if women of any reproductive age were struggling to get pregnant, the refined information could be used to indicate whether their AMH levels are normal for their age or below average. This could suggest how soon they might have to start thinking about fertility treatment such as IVF.

But Nelson said he would not recommend women in their 30s delaying having a baby because the AMH test appeared to suggest they had a certain number of fertile years left.

"It might be useful if you are much younger and in your 20s, but not in your mid-30s. For example, Down's syndrome risk is one in 250 at 35, but by the time you are 40 it is one in 100," he said. "If you wait those few years that risk is going to increase."