Fertility doctors believe they have cracked the secret of how to give women in their early 40s a similar chance of having a child via IVF as those a decade younger.
Official figures show that women in their early 40s have only a 13pc chance of conceiving per treatment.
But the new approach, hailed by a British pioneer as "potentially revolutionary", gives 40-year-olds a 60pc chance of becoming mothers with a single round of IVF.
It involves thoroughly testing embryos for major genetic abnormalities, the main reason why middle-aged women so often struggle to conceive. Genetically normal embryos are then frozen for a month or two, to allow women's hormones to settle after IVF drug treatment, before being thawed and inserted in the womb.
Today scientists will present the results of a trial showing that the approach, which costs between £2,000 (€2,458) and £3,000 (€3,688), almost doubles the chance of IVF pregnancy in women who are in their early 40s.
At a meeting of the American Society of Reproductive Medicine in San Diego, they will say that it took the successful pregnancy rate in a group of 38 to 42-year-olds from 33 to 61pc.
Dr Mandy Katz-Jaffe, of the Colorado Centre for Reproductive Medicine, said: "If she's 41 or 42, she's still got a 60pc chance of implantation. She has the same chance as someone who is 32."
Their trial of 60 women pitted current IVF techniques, which rely on choosing the best embryos by looking at their shape under a microscope, against what is known as complete chromosomal screening (CCS).
CCS involves checking that embryos have exactly 46 chromosomes, a set of 23 from each parent. Chromosome number errors can cause conditions such as Down Syndrome, but more frequently lead to early miscarriage. As women age, the quality of eggs and resultant embryos rapidly declines. By 40, 75pc of embryos are abnormal. By 42, 85 to 90pc are.
However, if the few normal ones can be identified, the chance of a successful pregnancy rises rapidly.
Dr Katz-Jaffe said: "If a woman aged 38 to 42 has an embryo with a normal number of chromosomes, her chances of (successful) implantation are independent of her age."
Recent studies indicate delaying implantation alone also boosts pregnancy rates, so combining the two techniques could be the optimum treatment.
Dr Dagan Wells, a British geneticist who helped pioneer embryo screening at University College London in the 1990s, said: "I think the evidence is starting to mount up that chromosome screening may be ready for prime time." (© Daily Telegraph, London)