Researchers say they noticed a defect in the eggs of mice that may also develop in women as they surpass the age of 35.

Every woman in her 30s knows she has a biological clock ticking.

Everyone around her knows it too.

For some women, this is no big deal. Either they’ve already had children or they have made the decision not to have them.

But for women who still yearn to be mothers, that clock becomes louder and louder the further into their 30s they get.

As most women know, 35 seems to be the magic number when doctors start to get nervous about a woman’s fertility.

The reasons for that heightened sense of urgency are well documented.

There are countless studies depicting the decline of female fertility with age, which is why the American Congress of Obstetricians and Gynecologists released a committee opinion reflecting that clinical and scientific data in 2014.

In that opinion, they cited research that found that over the course of 12 insemination cycles, 74 percent of women younger than 31 achieved pregnancy, 62 percent of women aged 31 to 35 had similar success, and only 54 percent of women over 35 were able to get pregnant.

In addition, a consistent increase in miscarriage rates has been found as women progress through their 30s.

Read more: Fertility options for women and men »

Investigating the reasons, the general rule of thumb is that women over the age of 35 trying to conceive should receive more aggressive treatment than those under 35.

None of this is new information. But the problem is, the scientific and medical communities have yet to come up solid reasons for why this happens.

Previous studies have hypothesized the “cohesion loss” theory as an explanation for why this decline occurs.

That theory was predicated on the concept that older eggs suffered from a loss of cohesion as the “glue” that holds the chromosomes together ceased to work as well.

However, a recent study involving mice points to another potential complication.

Research released early this month out of the University of Montreal Hospital Research Centre has found that older eggs in mice also appear to have instability at the microtubule level. That contributes to abnormal cell division.

While these microtubules typically assemble a “spindle in a controlled symmetrical fashion,” in older eggs, the microtubules instead assemble in all directions.

But how accurate are these mice studies in predicting what is responsible for the decline in female fertility among the human population?

Healthline reached out to Dr. Alan Copperman, director of the Division of Reproductive Endocrinology and Infertility at RMA of New York, with that very question.

“The mouse model is often relied upon as the primary mammalian model for genetic research, since despite there being some differences with regard to ovarian senescence, or aging, mice ovaries express many genetic and physiological similarities to humans,” he explained.

Read more: Agencies make infertility treatments affordable for women with low incomes »

So … we may now have a better idea of what causes the decline in fertility women begin to experience in their 30s.

But what good does knowing the reasons really do?

According to Copperman, it could potentially do a lot of good.

“Ovarian aging is the most common limiting factor to a woman/couple’s success of conceiving a healthy pregnancy,” he explained. “Understanding the mechanisms by which aging eggs acquire problems with their cellular machinery that lead to an imbalance of genetic material could one day help us to find a therapeutic target for treatments to address the problem of ovarian aging and its effects on embryo quality.”

Which means that this latest research could actually help to contribute to a solution further down the line.

That’s certainly a goal the researchers have in mind.

“We are currently exploring possible treatments for eggs that might one day make it possible to reverse this problem and rejuvenate the eggs,” Greg Fitzharris, a co-author of the Montreal study, and an associate professor at the university, said in a press release.

Could we really be heading toward a future where turning 35 doesn’t mean a woman will then be reminded of her ticking clock by ever person she meets?

The research is still many years off from getting to that point, but with a growing understanding of the mechanisms that contribute to female fertility decline comes a greater ability to address those issues.