The reproductive years of a woman are at their peak before the age of 30. Beyond that, fertility starts to decline, and by the age of 40, fertility potential is about half the level it was before 30 years old. Many women experience fertility issues, but now a new study on mice may help reverse the clock on eggs, offering new fertility hope to older women.
A team of scientists at the University of Queensland reports that they have lifted fertility rates in older female mice with the use of a compound, which can reverse the aging process in eggs. The discovery may pave the way for human use in the future, offering hope for some women who are struggling to conceive.
When women reach the age of 40, conceiving is harder and nearly impossible for some women. This loss of fertility is due to poor egg quality, something that becomes a problem in developed countries where women would wait until they're older before they get married and bear children.
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Published in the journal Cell Reports, the study highlights reversing the fertility clock, improving egg quality that's important for pregnancy success. The team found that losing egg quality due to aging was because of the declining levels of a cell molecule that's vital for producing energy.
Taking an oral dose of a precursor compound, which is utilized to create the molecule, can help boost fertility. The molecule called nicotinamide adenine dinucleotide (NAD) and the precursor, nicotinamide mononucleotide (NMN), are key drivers to promote reversal of aging fertility.
To arrive at their findings, the team treated aging female mice with low doses of NMN infused in their drinking water for one month. They found that the mice had restored egg quality and increased live births during a breeding trial.
Assisted reproductive technologies
The new treatment, if applicable to humans, can help maintain and restore egg cell quality during aging. Further, it helps reduce a rate-limiting barrier to pregnancy for older women. With more aging women facing fertility problems, there had been a sharp increase in the demand for assisted reproductive technologies, including In vitro fertilization (IVF).
However, since the study involved mice models, it's essential to conduct further research on humans to determine if the effect of the compound is the same.
"IVF cannot improve egg quality, so the only alternative for older women at present is to use eggs donated by younger women," UQ's Professor Hayden Homer said in a statement.
"Our findings suggest there is an opportunity to restore egg quality and, in turn, female reproductive function using oral administration of NAD-boosting agents – which would be far less invasive than IVF. It is important to stress, however, that although promising, the potential benefits of these agents remains to be tested in clinical trials," he added.
Infertility by the numbers
Infertility is a growing concern among couples who are having a hard time conceiving. The Centers for Disease Control and Prevention (CDC) defines infertility as the inability to get pregnant after one year of unprotected sex; it may be longer for some. For women who are 35 years old and beyond, doctors may begin treatment if they fail to conceive within six months of regular and unprotected sex.
In the United States, about 6 percent of married women between the age of 15 and 44 are having problems conceiving after one year of trying. Moreover, approximately 12 percent of women of the same age group have issues getting pregnant or carrying a pregnancy to term.
About 12 to 13 of 100 couples have trouble becoming pregnant in the country, while ten in 100 or 6.1 million women have problems getting pregnant. Fertility issues in women cause one-third of all infertility cases.
Worldwide, one in every four couples in developing countries are experiencing infertility, but the exact rates are hard to determine. The latest data were responses from women in Demographic and Health Surveys in 2004. However, in a 2010 study by the WHO, it shows that the rates in 190 countries remained similar to the estimated numbers between 1990 and 2010.
U.S. Centers for Disease Control and Prevention (CDC). (2019). Infertility FAQs: Frequently Asked Questions. https://www.cdc.gov/reproductivehealth/infertility/index.htm
World Health Organization (WHO). (2012). Global prevalence of infertility, infecundity and childlessness. https://www.who.int/reproductivehealth/topics/infertility/burden/en/
Bertoldo, M., Listijono, D., Ho, W.H.J., Sinclair, D., Homer, H., and Wu, L, NAD+ Repletion Rescues Female Fertility during Reproductive Aging. Cell Reports. https://linkinghub.elsevier.com/retrieve/pii/S2211124720300838