Ovarian reserve and number of eggs a woman is born with - biological age
When a female is in her mother’s womb she has about 7 million eggs during the fifth month of pregnancy. However a significant reduction in this number takes place resulting in only 2 million eggs left in the ovaries at birth.
Egg (oocyte) numbers drop off further such that by the time of puberty or when regular period starts, less than half a million eggs remain within the ovaries.
Unfortunately the ovaries cannot grow or create new eggs after birth. This is in stark contrast to sperm which can continue to be produced by the male testes until the later decades of life.
One of the biggest challenges facing Fertility specialists is how to optimize the chances of older women getting pregnant. This is because older women not only have fewer egg number, the quality of eggs declines with increasing age.
This change of egg quality with increasing age leads to poorer embryo quality and therefore:
- A lower chance of pregnancy.
- Higher risk of miscarriage
- Higher risk of abnormalities such as Down’s syndrome.
The quality of eggs vary from one woman to another and also within each ovary there are differences in quality. For this reason, there is also a difference in egg quality based on your chronological age (your actual age) and biological age referring to your actual ovarian reserve.
Everyone of reproductive age i.e. between the ages of 15 and 45 years, has the ability to conceive, however, the probability would be much lower at the extremes of this range of particular so towards the later years such as over 42 years of age.
The key message from the fertility planning point of view, is to try and conceive at a younger age. Understandably this is not possible for many nor desirable, as such measures to preserve your egg quality would be advisable such as having a healthy diet and avoiding smoking.
In addition there is promising evidence from research that suggest supplements e.g. testosterone like substances such as DHEA can be used to potentially enhance the chances of success. Anecdotally I’ve also found this to be the case in selected patients I’ve tried this on particularly if used for more than 4 months before IVF or ICSI treatment. However, further research in this area is still required.
For some the option of egg freezing should be considered, and this has to be weighed carefully taking into account your personal circumstances, age, egg (oocyte) and ovarian reserve as well as success rates. This should be discussed only with a fertility specialist familiar with this practice and treatment.
Whilst age remains the most generic and non-specific indicator of egg quality and reserve, more specific tests such as anti-mullerian hormone (AMH), ultrasound scan of the ovaries - antral follicle count (AFC) are currently the best and most reliable test available. Follicle stimulation hormone (FSH) measurement can be used but has to interpreted with caution and ideally an estradiol (E2) measurement should be done at the same time to know if it’s a true reflection of your ovarian reserve.
These test result can give you an idea of your own egg reserve. There are now research studies that confirm a link between egg reserve and the success of fertility treatment such as IVF or ICSI.
Sadly in some case where the egg reserve is very depleted or in much older women, by far the best chance of success would be with egg donation treatment. Where eggs from a young healthy donor are used with IVF or ICSI treatment to help you conceive. Success rates are usually over 50% per treatment cycle.
Luckily for most this treatment won’t be required and conceiving with your own eggs would be what happens.
For information on egg donation treatment see here.