Follicles, ovulation and fertility
Is female fertility affected by age?
Yes. And the reason is very clear. Women are born with a certain number of follicles, which they "spend" throughout their fertile life.
The eggs are created when women are still embryos in the womb. At about 20 weeks of age, the female fetus has about 5 million eggs in her ovaries. At this stage the production of new eggs stops.
From these 5 million eggs, about 80% degenerate by birth, leaving the newborn baby girl with 500.000 – 1.000.000 eggs, which are what she will use during her fertile phase. This number of eggs is called the Ovarian Reserve. (A useful test is the one that measures FSH levels, which is an indicator of your reserve, before spending on other costly tests).
The eggs are inside the follicles. In each cycle 30-40 follicles will begin to develop, but usually only one of them will reach ovulation and release an egg. The rest will degenerate.
So, a woman will ovulate about 400 times during the fertile phase of her life.
Interestingly, at the age of 30, women will have available about 12% of the eggs they had when they were born. This number may seem small, but it is able to support fertility for years to come and until menopause.
Can modern medicine change the data?
New researches suggest that new eggs can be produced by stem cells. However, this process is still very complicated and in an experimental stage.
In conclusion, women have a certain number of eggs to use. In the future this may change with the production of new eggs in laboratories. Until then, however, we must take full advantage of the fertile period of our lives.
So, with the help of our ovulation tests, you know your exact fertile window in each cycle, making sure that your efforts are productive and reducing the factor of “luck” during this period.
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