The very few women who have children after the age of 45 may be capable of doing so because anti-ageing mechanisms are more active in their bodies.
Neri Laufer’s team at Hadassah University Hospital in Jerusalem recruited eight women who had given birth naturally after the age of 45. “They are an extremely unique group of patients,” he says. “They are very successful breeders.”
His team compared levels of gene expression in the women’s blood from with levels in six mothers of the same age who had chosen not to have any more children after 30. They found differences in 716 genes.
Intriguingly, many of the genes that were more active in the fertile over-45s are involved in repairing DNA damage and preventing cell death. That would help counteract the effects of ageing, especially ageing of the ovaries, Laufer told a meeting of the European Society for Human Reproduction and Embryology in Copenhagen, Denmark, on Tuesday. His team also plans to look at whether the women live longer, too.
Born with it
It is possible that having lots of children causes these differences – the fertile over-45 group had an average of nine children each compared with just two for the controls – but Laufer thinks it more likely that the women were born with this propensity. Their miscarriage rate was far lower than normal, he points out, and did not change as they had more children.
All the women were ultra-orthodox Ashkenazi Jews, but Laufer says preliminary results from a study of Bedouin women suggest the results apply to all. If so, it might be possible to test young women’s gene expression patterns and predict how long they will remain fertile.
The findings should also lead to a better understanding of why fertility declines sharply in the years leading up to the menopause – and in the long-term might even lead to treatments that extend fertility, Laufer speculates. But if DNA damage in the ovaries is to blame, there will be no easy way to reverse it.
And although a few women may be fortunate enough to remain fertile past the age of 45, delaying childbirth this late is dangerous, says Michael de Swiet of Queen Charlotte’s Hospital in London, UK. Many older women find pregnancy a miserable experience, he says, and the risks of complications increase dramatically beyond this age: the risk of dying is 10 times as high compared with women in their early 20s, for example.
