Older mums may risk fertility of daughters
Wednesday October 25 2006
MOTHERS who have baby girls in their late thirties and forties may be compromising their daughters' chances of starting a family when they grow up, scientists have discovered.
Advancing age not only reduces a woman's ability to conceive but also raises the risk her female offspring will struggle to conceive later in life, research says.
The findings are alarming because women are increasingly postponing having children until they have established a career.
One in seven couples already has difficulty becoming pregnant, and this will worsen as more daughters of older mothers reach adulthood and try to conceive.
In Britain, half of all births are to mothers over 30, compared with 27pc 20 years ago.
Over-35s account for 9pc of first births, more than twice the figure 20 years ago.
Peter Nagy, of Reproductive Biology Associates in Atlanta, who led the study, said: "If we think of our parents, most of them were relatively young when we were born. Today society is changing, and a lot of women are delaying childbirth.
"What we see in 20 to 30 years' time will be completely different. We are likely to see more fertility problems in the future."
Any such effect could be heightened by the growing popularity of a type of IVF known as intra-cytoplasmic sperm injection, or ICSI, which was developed to treat male infertility and now accounts for about half of all procedures.
Decline
Because ICSI involves injecting an egg with a single sperm, which might not have been capable of fertilising it, concerns have been raised that boys born in this way could also grow up to be infertile.
And it has long been understood the quality of a woman's eggs worsens as she approaches the menopause, causing a sharp decline in her fertility after the age of 35.
Dr Nagy asked female IVF patients how old their mothers were when they were born, and at what age they went through the menopause. This allowed him to calculate the "biological age" of the mothers' ovaries, by comparing age at menopause with the age at which their daughters were born.
He found that the women were more likely to become pregnant if they were born to relatively young mothers, suggesting that being born to an older mother has a negative impact on fertility.
"I believe the correct conclusion is that maternal age and reproductive age is an important determining factor not only for the patient herself, but also determines to a certain extent the chances for her daughters," he told the American Society for Reproductive Medicine conference in New Orleans yesterday.
"When we are treating patients at around 40, we are helping them to get babies, but the children will probably have a higher risk of ending up as infertility patients themselves. For every year of increase in age, it could be more difficult for the daughter." (© The Times, London)
- Mark Henderson
