London: For the first time, scientists have developed a simple hormone test that could measure how fast a woman`s biological clock is ticking, a move they say could revolutionise family planning by predicting when a woman is likely to start the menopause.
The test devised by a team from St Andrews University in Scotland allowed the researchers to successfully chart levels of a vital fertility hormone in women of different ages.
It could also show how long a woman can delay motherhood and save couples expensive from opting in vitro fertilization treatments by predicting their chances of successful conception, the researchers said.
Tom Kelsey, who helped the research, said it was already known that high levels of the fertility hormone 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," he was quoted as saying by the Daily Telegraph.
In the study, the scientists compared the levels of anti-Mullerian hormones (AMH) -- reflects ovarian activity and give an estimate of remaining egg supply -- in 3,200 healthy women to show accurately how the range changed with age.
Doctors claim they will be able to use the results as a benchmark against which to measure others, indicating when they are likely to go through the menopause and how long they will remain fertile.
According to researchers, women are born with a finite supply of eggs -- on average between one and two million -- which are shed as part of the monthly cycle until menopause.
A woman`s ability to conceive declines substantially after her mid-30s, although the speed varies person to person.
Richard Anderson, professor of reproductive medicine at Edinburgh University, said: "Predicting how long you might remain fertile can be very important, and it seems that AMH can help in this."
The news comes just weeks after women were given a stark warning of the risks they face in delaying motherhood.