Becoming a mother at 50 could be the norm within the next decade, say scientists who have successfully ‘reverse-aged’ human eggs.
In a major breakthrough, Israeli researchers effectively made eggs from 40-year-old women resemble those of twenty-somethings.
Women are born with all of their eggs but they deteriorate over time, making it more difficult for older eggs to be fertilized.
While the average female in her early 20s has an 80 per cent chance of becoming pregnant naturally within a year, this halves by the age of 40. Just a few hundred women in the UK become mothers in their 50s each year.
But scientists at Hebrew University of Jerusalem have shown the deterioration could be reversed with an antiviral used to treat HIV patients.
It is thought to work by preventing DNA damage that happens during the aging process with a drug that blocks genetic damage during viral infections.
There are still questions about whether the process can boost fertility rates because the study did not expose the treated eggs to sperm.
But the team now plan to test this on animals and then eventually humans. It is also hoped the treatment could reduce the risk of miscarriages and birth defects, which are more common with older mothers.
Scientists at Hebrew University, Jerusalem, exposed human embryos to an antiviral drug and found it repaired many genetic errors – making them like those of a woman in her 20s (stock)
What are the chances of getting pregnant in later life?
Women are born with all of their eggs, but they deteriorate over time.
This makes it more difficult for an older woman to get pregnant.
Below are the estimated chances of getting pregnant naturally:
- Early 20s and late 20s, 80 per cent;
- Early 30s, about 70 per cent;
- Late 30s, about 60 per cent;
- Early 40s, 20 to 40 per cent.
More than eight out of ten couples where the woman is under 40 will get pregnant naturally, charities say.
But in some cases they will need to turn to fertility treatments to raise their chances of getting pregnant.
This includes IVF, where an egg is fertilized in a test tube and then implanted into the patient.
Below are the chances of getting pregnant per round of IVF, by age.
- 35 to 37 years old, 23 per cent;
- 38 to 39 years old, 15 per cent;
- 40 to 42 years old, nine per cent;
- 43 to 44 years old, three per cent;
- Over-44 years old, two per cent.
The NHS tends to offer three cycles of IVF to women under 40, although in some areas this treatment is not available.
It may also offer one cycle of IVF to women aged between 40 and 42 years old.
During the aging process in an egg, parts of its DNA can start attacking other areas in a similar way to how viruses can replicate.
To stop this, the scientists theorized that an antiviral called a reverse-transcriptase inhibitor used to prevent DNA damage in viral infections could help.
Dr Michael Klustein, the molecular biologist who led the research, told the Times of Israel: ‘Many women are trying to get pregnant aged 40 and over, and we think this could actually increase their level of fertility.
‘Within 10 years, we hope to use antiviral drugs to increase fertility among older women.
‘This may help women between the ages of 40 and 50. After that, we hit the menopause.’
He added: ‘Because the attacking DNA behaves like a virus, we hypothesized that antiviral medicine administered to eggs may reverse age them and rejuvenate them, and found in our lab that this is the case.
‘We tested hundreds of mouse eggs and then human eggs, which confirmed the hypothesis.’
Bragging about the results in a press release, the team claimed that the older mouse eggs that were treated ‘returned to their former youthful selves’.
The drug was first tested on hundreds of mice embryos, before being used on leftover human embryos from IVF treatments.
The scientists stress they have not yet tested introducing sperm to the treated eggs, so have not proved whether it enhances fertility.
Women are now having children later than ever in the West.
In the UK, the average age of first time mothers is now 29 years old – compared to 23 in the 1970s – with many delaying having children into their 30s.
In the US, it has risen from 21 to 26 years old.
The change is believed to be due to more women prioritizing their careers, as well as changes to society and financial concerns.
But the chances of falling pregnant drop as women age.
Studies suggest it is as low as five per cent once a woman is more than 40 years old.
To get around this, many women are now having eggs frozen when they are younger in preparation for fertility treatment later in life.
About 50,000 women use fertility treatment every year in the UK, while in the US it is more than 90,000.
Success rates for IVF treatment are about 25 per cent – or one in four embryos – for women aged between 35 and 37 years old. For those under 35, rates are about 32 per cent.
The study was published in the journal Aging Cell.