Doctors have developed a test to predict the chances of successful fertility treatment in women over 40 years of age.
The test is being made available over the internet and measures three hormones that together indicate how many eggs a woman has left in her ovaries.
Specialists at the assisted conception unit at Jessop hospital in Sheffield are recommending the test to older women and those with a history of fertility problems to help them make informed decisions before paying for fertility treatment.
More than one in seven women in England and Wales conceive over the age of 35. Researchers said the test would help older women to decide whether to proceed with treatment, and to prepare psychologically for failure if the test suggested they had a low chance of success.
Doctors believe the test will help reduce the number of fertility cycles which have to be abandoned, and save money from being wasted on treatment which is extremely unlikely to work.
Bill Ledger, who led the team, said: "It's hard to dissuade women from having a go at IVF even when they're older and the chances are it's not going to work. We wouldn't propose stopping people having IVF if the test result was bad, but we hope this will help with counselling if their treatment does turn out to fail."
In an editorial in the British Medical Journal last year, fertility specialists including Susan Bewley, a consultant obstetrician at Guy's and St Thomas' hospital in London, warned women that by delaying having children they risked "defying nature and risking heartbreak".
Figures from the Human Fertilisation and Embryology Authority show that fertility rates plummet beyond the age of 35, reaching almost zero by 45. Miscarriage also becomes a risk the older women conceive. At 40, the risk is double that at 20 years, with 40% of all pregnancies leading to miscarriages.
The test measures levels of two ovarian hormones, called inhibin B and anti-mullerian hormone (AMH), and follicle stimulating hormone (FSH), that together indicate how many eggs a woman has left in her ovaries.
In a report published today in the journal Human Reproduction, the researchers tested blood from 84 women aged 40 or older before they were given fertility treatment.
Thirteen patients - 15% - had their treatment cancelled because they did not respond to drugs and 48 patients - 57%, produced four eggs or fewer. Typically, fertility clinics hope to collect 12 eggs from women after treatment.
The researchers found that levels of AMH and the two other hormones were able to predict which patients would not respond well to treatment and which were at risk of having their therapy abandoned.
The Sheffield team have been supplying the test privately, but are now making it available publicly on boots.com for £179 under the name Plan Ahead.
