Researchers Have Found A New Reason Older Women Struggle to Conceive

What makes a woman’s biological clock tick? Until now, it was widely thought that changes to a woman’s eggs (part of the natural aging process), is what makes it harder to conceive as women approach menopause. But new research suggests that's not the full story: The age of a woman's uterus matters, too.

New research presented at the annual meeting of the European Society of Human Reproduction and Embryology (ESHRE) shows that even when women use (younger) donor eggs, their chances of becoming pregnant begin to fall steeply from the age of 49 — nearly 15 percentage points lower than for those aged 35-40. Meanwhile, miscarriage rates (with donor eggs) in the older age group are almost 38%, compared with 24% among the younger age category.

This new research indicates that in addition to aging eggs, the way the uterine lining develops in women over 49 makes it less receptive to embryos — a double whammy for older women trying to get or stay pregnant. 

"For many years, reproductive aging has been seen primarily as an ovarian issue," said Dr. Beatrice Crestani, the paper's lead author. "Our findings suggest the picture is more complex."

Crestani did point out that even in the older age group, birth rates for women using donor eggs are "meaningfully” better. Some 32% of over-49 year-olds gave birth after treatment with donor eggs, according to the findings, while success rates for women over 45 using their own eggs are less than 2%. So, as Crestani pointed out, donor eggs are definitely worth a try in this age group. 

Still, ask most doctors if women should bear children at an older age, and they'll say no. Having a baby is hard on a woman's body, and the older she is, the greater the risks. Women in their 40s are at greater risk of high blood pressure, a low-lying placenta, pre-eclampsia and gestational diabetes. 

That hasn’t stopped companies from developing ways to help women keep reproducing for as long as possible. 

At the ESHRE meeting which I attended in London earlier this month, the company Lumiris touted technology that it says can identify a human egg's "metabolic age," — i.e. how "mature" it is — which, it says, could help women determine whether to freeze their eggs, or could help fertility specialists select a woman’s optimal eggs for creating embryos. Another company, Future Fertility, claims its tool can provide a probability of pregnancy just by looking at a woman's eggs. It's futuristic stuff.

And then there’s Conception, a company backed by OpenAI's Sam Altman, which claims to have made human egg cells from blood cells. It was, Conception said, creating "freedom from biological and genetic limits." Extrapolate that and you can see a scenario in which a woman could bypass the eggs she already has for new, fresh ones, which haven't been subjected to the aging process at all.

Do we need all this? Figures from the U.K.'s Office for National Statistics suggest women will continue to have babies later, driven by "financial pressures and the timing of other life events such as partnership formation and moving into your own home generally happening later."

Or, we could just make it easier and less costly for women to have babies in their younger years. Now there’s a thought.