Study finds way to 'time' women's biological clock, the predictions, from age 20, are accurate to four months
Women who want a career and a family can hardly fail to be aware these days of the biological clock ticking. What they don't know is whether their own clock is fast or slow — and how long they can safely leave it if they want a child.
But now scientists hold out hope of a simple blood test they say can predict the date of a woman's menopause, to within four months. If their work can be confirmed by larger studies, women will be able to have a much clearer idea of how long they are likely to remain fertile.
The test measures the concentrations of a hormone that is produced by cells in the ovaries. Iranian scientists who present their work to the European Society of Human Reproduction and Embryology in Rome tomorrow, say that the hormone level can help to predict when a woman as young as 20 will reach the menopause.
During the study, 63 women reached menopause, and on average they found the test had been accurate to within four months. The biggest margin of error was three to four years.
On average women reach the menopause around the age of 52. A test would enable them to plan their families, taking into account that their natural fertility would be in steep decline around 10 years before menopause. Those who want to delay having children could be reassured.
But the test would be most useful for the small proportion of women who go through an early menopause — around 1% under the age of 40 and 5% to 10% under the age of 45. While many may expect it, because often it has happened to their mother or aunt before them, some are taken by surprise.
"The results from our study could enable us to make a more realistic assessment of women's reproductive status many years before they reach menopause," said Dr Fahimeh Ramezani Tehrani, who is president of the reproductive endocrinology department of the Endocrine Research Centre and a faculty member and associate professor of Shahid Beheshti University of Medical Sciences in Tehran.
Tehrani's team accept that their study was small and will need to be replicated on a larger scale before any test could be widely introduced.
The blood test detects levels of anti-Müllerian hormone (AMH), which controls the development of follicles in the ovaries, from which oocytes (eggs) develop.
The researchers took blood samples from 266 women, aged 20 to 49. They measured the women's concentrations of AMH and collected two further blood samples at three-yearly intervals.
They also collected information on the women's socioeconomic background and reproductive history, and examined them every three years. Based on the AMH concentrations, they estimated when menopause was likely to occur for women at different ages and different stages of their reproductive lives.
Higher levels of the hormone predicted later menopause than low levels.
"If a 20-year-old woman has a concentration of serum AMH of 2.8 ng/ml [nanograms per millilitre], we estimate that she will become menopausal between 35 and 38 years old," said Tehrani.
"To the best of our knowledge, this is the first prediction of age at menopause that has resulted from a population-based cohort study. We believe that our estimates of ages at menopause based on AMH levels are of sufficient validity to guide medical practitioners in their day-to-day practice, so that they can help women with their family planning.
"Our findings indicate that AMH is capable of specifying a woman's reproductive status more realistically than chronological age per se".
He added: "Larger studies, starting with women in their 20s and following them for several years are needed to validate the accuracy of serum AMH concentration for the prediction of menopause in young women".
Nick Macklon, professor of obstetrics and gynaecology at Southampton University, said other work on measuring AMH suggested it may offer the best prospect for devising a test to measure how long a woman will remain fertile.
"It can give us a reasonable idea of when the menopause may happen, but more importantly when women's fertility may fall and they can't have a spontaneous conception," he said.
"What is lacking are the prospective long-term studies which correlate the predicted time on menopause with the actual time of menopause".
Stuart Lavery, director of in-vitro fertilisation at Hammersmith hospital, London, and a spokesman for the British Fertility Society, said: "One issue of concern is if people become too reassured about this. They might think that if their AMH at age 25 is 'X' they don't need to be too concerned. But there can be other factors.
"It's going to be important how this test is perceived, so people don't think all they have to do is pop in and get insurance against their biological clock ticking".
Dr Dagan Wells, of Oxford University, said: "Remember fertility can be dramatically reduced in the years leading up to the menopause, for five years or more.
"Where this test might be particularly useful, even if it's not super-accurate, could be where women are unaware they might experience a very premature menopause. It could give them a heads-up".
