Doctors are a step closer to accurately¹ predicting the age at which a woman will hit the menopause.

医生能够准确预测女性进入更年期的年龄仅有一步之遥。

Blood tests were used to measure levels of AMH

A 12-year Iranian study of 266 women found it was possible to pinpoint²（查明，精确找到） the age of menopause by measuring levels of a hormone³ called AMH.

If proven in further studies, it potentially means women could have more control over when to start a family.

It could be particularly useful for identifying women who may have an early menopause, experts said.

AMH controls the development of follicles（淋巴结，小囊）in the ovaries（卵巢，子房） from which eggs develop.

The idea of using the hormone to help predict fertility is not a new one.

Tests are already available to look at "ovarian reserve", which indicates if menopause（更年期） is imminent⁴（即将来临的，迫近的） .

But this is the first time researchers have worked out a formula for linking AMH levels in younger women with future age of menopause.

In the study 266 women aged⁵ between 20 and 49 were monitored through blood samples and physical examinations at three-yearly intervals⁶ over a 12-year period.

The researchers, who presented the results at the European Society of Human Reproduction and Embryology conference in Rome, then worked out a mathematical model（数学模型） for estimating the age at menopause from AMH levels in the blood.

For the 63 women who reached menopause during the study there was consistent agreement between their "predicted" age and actual age of menopause.

On average, the difference between the predicted and actual age of menopause was only a third of a year, with a maximum margin⁷ of error of three to four years.

However only three of the women under the age of 45 hit the menopause during the study, so experts said they would like to see the formula tested in a much larger group to prove its accuracy.

'Insurance policy'

The study leader, Dr Fahimeh Ramezani Tehrani, from the Shahid Beheshti University of Medical Sciences in Tehran, Iran, said the results could enable doctors to make a more realistic assessment⁸ of women's reproductive status "many years before they reach menopause".

UK doctors said using AMH as a guide to future fertility was proving potentially very useful but warned women against relying on such tests as an "insurance policy" encouraging them to put off（推迟，延期） having a family.

Stuart Lavery, a consultant⁹ gynaecologist（妇科学家） at Hammersmith Hospital in London and spokesman for the British Fertility Society, said that the quality of the partner's sperm¹⁰ and other medical complications such as scarred tubes all contribute to overall fertility.

"The issue where we would have a concern is if people become too reassured¹¹（消除疑虑的，放心的） by this."

Dr Dagan Wells, senior scientific the Nuffield Department of Obstetrics and Gynaecology at the University of Oxford¹², said: "Given that women are tending to start their families later and later, postponing¹³ having a child until careers are established or until 'Mr Right' comes along, foreknowledge of the length of their fertile lifespan should help them to plan ahead."

But he said that fertility declines in the years leading up to menopause, so more research is needed to work out if AMH levels can determine the point at which fertility actually drops.