(The Center Square) - Girls are born with a million small structures called primordial follicles. Each of these contains an egg cell. As girls grow and develop, most of these follicles die, and each month, just one follicle typically ovulates a mature egg.

"When the loss of primordial follicles is nearly complete, and only hundreds remain, women experience menopause, a time when menstrual cycles have ceased for 12 months," a release from the University of Utah said.

New research, which uses a model developed by a University of Utah mathematician, contends that it may be possible to delay the onset of menopause indefinitely by removing and then implanting a woman's ovarian tissue back into her over and over again. The study was funded by the National Science Foundation.

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The technique has been used to help restore fertility in cancer patients, according to Sean Lawley, associate professor of mathematics and co-author of a study published earlier this month in the American Journal of Obstetrics and Gynecology.

The work is a collaboration between Lawley, University of Colorado School of Medicine ovarian biologist Joshua Johnson; Yale University professor of statistics and data science Jay Emerson; and Yale School of Medicine physician and professor of obstetrics, gynecology, and reproductive sciences and ovarian biologist Kutluk Oktay.

In the late 1990s, Oktay created methods to harvest ovarian tissue from young cancer patients, freeze it, and transplant it back into her once she had undergone cancer treatments that would have caused her to be menopausal and infertile. It is known as “ovarian tissue cryopreservation and transplantation.”

The technique has let hundreds of cancer survivors conceive and give birth to children. It is different than freezing eggs and in vitro fertilization, which does not impact menopause.

“A lot of the interest behind delaying menopause is fertility, but a lot of it also comes from the idea that functioning ovaries are better for a woman’s health,” Lawley said. “Menopause is associated with many health issues relating to cardiovascular disease, bone density, obesity, etc. Keeping ovaries functioning longer might delay or even prevent these health issues from starting.”

“Math is being used to address the question of how long you can delay menopause and how that depends on different factors," Lawley added. "We have developed a model of how ovaries age. The data comes from a number of places, chiefly from primordial follicle counts inside ovaries.”

Oktay, an expert in fertility preservation, pondered if ovarian tissue cryopreservation and transplantation procedures could help healthy women delay menopause and the negative effects associated with it.

“In the past few years, we’ve been developing mathematical models of how the ovaries age and what triggers menopause,” Lawley said. “It was extremely exciting when he [Oktay] contacted our group to see if our model could be used to help explore whether this procedure could be used to delay menopause.”

The AJOG study found that the procedures Oktay pioneered for cancer patients could delay menopause for healthy women.

“We were faced with a number of important questions. The first is, will it work? Will it delay menopause, and by how much?” Lawley said in the release. “Next, how do you optimize the procedure? Are there age ranges that tissue should be removed? How does the number of follicles in a woman’s ovarian tissue influence how long the tissue will function?”

The team found ways to address such questions using mathematical modeling.

Their methods included developing an online calculator that shows how many years a woman could delay menopause by the procedure. The data from the paper suggests that the younger a woman is when she preserves her tissue, the longer she can delay menopause. 

“If ovarian tissue can be frozen under the age 30 years, in theory, menopause can even be eliminated in some cases,” the study said. “However, the feasibility and safety of delaying menopause beyond age 60 need to be clinically evaluated.”