Fertility in your late thirties and forties
More and more, women are choosing to wait until later in life to have children. In Australia, the average age of women at first birth in 2015 was 28.9 years compared with 28.1 years in 2005 and the proportion of births to mothers over the age of 35 years was 22% (1).
However, a woman’s age is one of the most important risk factors for suffering with infertility. This is mainly due to a decrease in the quantity and quality of gametes, which for a female is her egg cells (2).
A little more about egg quality
Egg quality is essential to a successful pregnancy as they have an important role in fertilisation, maturation and subsequent embryonic development (3).
Egg quality is also a major factor in achieving pregnancy through IVF. Yet, 1 in 4 women who undergo IVF treatment are aged 40 or older. The process of IVF cannot improve or alter egg quality, so the only alternative for older women at this current time is to use eggs donated by younger women (2).
Many tissues in the body undergo continual regeneration. Female eggs however, are laid down in the ovaries during in utero development in humans where they form a finite store of eggs for life that does not undergo self-renewal or regeneration (3). This means that human eggs are particularly susceptible to age-related dysfunction and decline.
Despite the increasing demand for increasing fertility in older women, there are currently no viable strategies for either preserving or improving egg quality during aging (3).
Exciting new research about restoring egg quality – there is hope!
Researchers have been able to increase fertility rates in older female mice with small doses of a compound that can reverse the aging process in eggs. This offers some hope to older women who are having trouble with conception and fertility (3)
The study looked at whether the reproductive aging process could be reversed by an oral dose of a ‘precursor’ compound called nicotinamide mononucleotide’ (NMN) used by cells to make the molecule nicotinamide adenine dinucleotide (NAD). NAD is essential in the body for energy metabolism, DNA repair, and gene expression and NAD levels are known to decline in tissues with age (3).
The researchers found that human egg levels of NAD decline with age. Repletion of NAD stores through oral administration of NMN can restore egg quality and subsequently enhance fertility rates (3).
So what now?
This promising research shows the potential for the development of orally delivered medications or supplements that could enhance egg quality in older women for natural conception or IVF. It could improve success rates of conception via IVF through improving embryo culture conditions and developmental outcomes. It would be a simple non-invasive intervention to improve fertility that could save couples a whole lot of stress, anxiety and money (3).
Although this research is promising, it is important to note, however, that the potential benefits of applying NAD to fertility remains to be tested in clinical trials. Thus, further research is required.
This article was written by Felicity Harvie as part of her internship with me in 2020.
References
1. Vollenhoven B, Hunt S. Ovarian ageing and the impact on female fertility [version 1; referees: 2 approved]. F1000Research. 2018;7(0):1–6.
2. García D, Brazal S, Rodríguez A, Prat A, Vassena R. Knowledge of age-related fertility decline in women: A systematic review. Eur J Obstet Gynecol Reprod Biol [Internet]. 2018;230:109–18. Available from: https://doi.org/10.1016/j.ejogrb.2018.09.030
3. Bertoldo MJ, Listijono DR, Ho WHJ, Riepsamen AH, Goss DM, Richani D, et al. NAD+ Repletion Rescues Female Fertility during Reproductive Aging. Cell Rep [Internet]. 2020;30(6):1670-1681.e7. Available from: https://doi.org/10.1016/j.celrep.2020.01.058