Women in the US are having children later in life than ever before.
The average age of a mother giving birth to her first child was 26 in 2013 — a record high, according to Centres for Disease Control and Prevention data, that includes plenty of women over 35 and even some over 40.
Dr. Norbert Gleicher, founder, medical director, and chief scientist of the Center for Human Reproduction fertility clinic in New York City, thinks this is a trend that is only going to continue. He predicts that advances in the field of reproductive technology will enable older and older women to give birth to their own biological children.
“We will reach a threshold where age no longer matters and women will be able to conceive probably pretty much independent of their age,” Gleicher told Business Insider.
It will take serious research to reach this still-hypothetical future where age is truly irrelevant to reproduction, but there are several areas that scientists are already working on to get us there.
Generating mature eggs in a lab
A woman’s age-related decline in fertility has been linked to a gradual decrease in the number and quality of cells that can mature into eggs in the ovaries (known as ovarian reserve), notes a report from the ASRM and American College of Obsetricians and Gynecologists (ACOG). Those cells that can become eggs are surrounded with other cells that take care of them and help them grow. The whole complex is called a follicle, and women are born with about a million of them.
Only a tiny fraction of follicles actually mature into eggs that could be fertilised, however. The majority are lost through a process called atresia.
But it could be possible, Gleicher suggested, to take a little bit of the ovary tissue with immature follicles and coax them to mature into eggs in the lab. Scientists have already done this in mice, and the eggs have yielded live babies after in vitro fertilization and implantation in mothers. Research is ongoing to get this to work in humans.
If scientists can manage this, doctors could save thousands of a woman’s eggs for future use, many more than egg freezing can — and without the hormone treatment.
Growing sperm and egg cells from regular cells
Another way to get more eggs than a woman’s body makes available naturally is to make them from normal body cells, called somatic cells. This can be done by first converting somatic cells into stem cells that can become many different types of cells in the body (known as induced pluripotent stem cells), then into egg cells.
Animal sperm and egg cells made this way have resulted in viable offspring, and scientists have succeeded in making human sperm from induced pluripotent stem cells. There are still significant questions about the safety and efficacy of this process, but Gleicher thinks making human eggs and sperm from somatic cells is an achievable goal in the next 10 years.
Screening embryos first
A key problem for older women trying to conceive is that their older eggs and the fertilised embryos that result are more likely to have genetic abnormalities that will prevent them from growing into healthy babies.
Right now that means older women have slimmer chances of having a baby through in vitro fertilization (IVF) than young women do, and the babies older mothers do have are more likely to have certain genetic problems.
During the process of IVF, multiple embryos are created in the lab from a couple’s eggs and sperm, sometimes more than will be transferred to the woman’s uterus in one attempt. To pick the embryos to transfer that have the best chance of leading to a healthy baby, doctors can take one cell from an embryo and analyse its DNA in a procedure known as preimplantation genetic screening.
It’s common for developing human embryos to have an abnormal number of chromosomes, so the goal of preimplantation genetic screening is to choose only embryos with the normal number of chromosomes to transfer to the woman.
Ideally this process makes IVF more efficient by only using the best embryos — but some say there’s not enough data to support doing the procedure generally.
Fertility specialist Dr. Kutluk Oktay thinks research in the next 4-5 years will make preimplantation screening more cost-effective and better able to test for things beyond just chromosome number.
With improvements to the technology, “we’ll be able to test embryos and increase success rates tremendously, and reduce the number of attempts,” he told Business Insider.
Editing human embryos
It’s a little further out there, but with recent news that scientists in China have edited the genes of human embryos — albeit with many ethical questions and technical glitches — Gleicher said it could eventually be possible to fix genetic abnormalities in the embryos of older women.
Those embryos would then be more likely to survive, and a major obstacle for older women trying to get pregnant would be treatable.
Supplementing older eggs
Besides genetic abnormalities, older eggs can have other problems. As cells age, their mitochondria — the part of a cell that generates the energy it needs to function — can sustain serious damage, Oktay said.
Scientists are working on ways to enhance the quality of eggs for women who have tried IVF but have not gotten pregnant because of problems with their eggs, an area of research Oktay calls “exciting.”
One way to enhance eggs, developed by the company OvaScience, involves supplementing an egg with mitochondria taken from stem cells found in the lining of a woman’s uterus. The procedure, called AUGMENT, is highly experimental and not yet FDA-approved. But the first babies conceived using the procedure abroad have already been born.
A lot of questions remain to be answered about how effective AUGMENT is for women trying yet another round of IVF, let alone the effects adding mitochondria to an egg cell may have on the children born after the procedure. Only time and much more research in larger groups of women will determine whether the new technology will be an effective option for older women who have had trouble conceiving.
‘Society better get ready’
Gleicher stresses that medicine is “evolutionary,” meaning progress happens slowly.
Predicting the timeline for the future of medical advances is always tricky, but he predicted some technical issues for older women trying to conceive will be resolved in the next 10 years. It could take another 10 years after that for the technological advances to be adapted into treatments women can actually benefit from, he said.
If we get to the point Gleicher anticipates when age isn’t the limitation on women’s fertility it’s always been, he and colleagues wrote in a recent paper, “medicine and society better get ready for this revolution.”
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