Typically, women are born with approximately one to two million ova. That sounds like a lot, but interestingly enough, female fetuses actually have far more egg cells when they are in the mother’s womb—sometimes as many as six or seven million eggs.
When egg cells are still immature, they are also referred to as oocytes. By the time a woman reaches puberty, there are only a fraction of those oocytes left—usually about 300,000.
During her reproductive lifespan, only about 500 of a woman’s eggs are ovulated. The remaining eggs that are left behind die out during menopause.1 A woman is considered to have gone through menopause when she has a thousand eggs or less in her ovaries.
Prior to menopause, women typically lose a thousand or so eggs every month. Egg death is a natural part of the cycle of the female reproductive system.2
Just as important as the quantity of a woman’s eggs is the quality of them. As women age, their egg quality declines due to an increased percentage of chromosomal abnormalities in eggs. When the quality of eggs declines, it can be harder for a woman to get pregnant. Eggs of poor quality may not fertilize, or, if they do get fertilized, it may not develop significantly enough to be implanted in the uterus. A low-quality egg could also fail to sustain health long enough to continue adequate fetal development even if implanted. So, egg quantity is not the only factor to consider while TTC—quality is just as important. 3
Every individual is unique, and while age is a determining factor in a woman’s fertility, it’s possible for a woman as young as 30 to experience egg quality or quantity issues, whereas a 43 year-old woman could still be fertile enough to achieve conception.
- Brzyski, R.G. and Knudtson, J. (2015) “Female Internal Genital Organs.” Merck Manual. Retrieved October 24, 2015, from http://www.merckmanuals.com/home/women-s-health-issues/biology-of-the-female-reproductive-system/female-internal-genital-organs ↩
- Nagourney, E. (2015 February 1). What Happened to All Those Eggs? New York Times. Retrieved October 24, 2015, from http://www.nytimes.com/2013/02/01/booming/womens-eggs-diminish-with-age.html?_r=0 ↩
- Sherbahn, R. (2015). “Female Age, Fertility and Infertility.” Advanced Fertility Center of Chicago. Retrieved October 24, 2015, from http://www.advancedfertility.com/age.htm ↩