Ovarian reserve – What determines how many eggs you have?

Every woman is born with a specific number of eggs (which is her ovarian reserve) and ovarian follicles. Given that this is the case, a natural question might be: what determines how many eggs you’re born with?

The answers come down to your own, individual genetics. That’s why there’s a lot of variation in the number of eggs that women are born with. In fact, it’s been estimated that – at the time of her birth – a woman can have anywhere between 35,000 and 2.5 million ovarian follicles (so it’s possible for one woman to be born with 50x more eggs than another woman!).

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Your genetics determines how many eggs you’re born with – and thus how many eggs you have today.

Thus, one of the key factors that affect your ovarian reserve today is how many eggs you originally had when you were born – which you can’t control or change.

There’s another major player when it comes to the extent of your ovarian reserve. During each menstrual cycle – a proportion of your ovarian follicles are “recruited” to begin the ripening process. But generally speaking, only one of these follicles actually releases its egg – the rest of the maturing follicles (and their eggs) are broken down. There’s good evidence that the number of follicles that are “recruited” each month varies depending on the individual.

For example, in one woman, 100 follicles might undergo the ripening process, whereas in another woman more than 5,000 follicles could begin maturing during her cycle. Of course, if this so-called “recruitment rate” is particularly high, then one’s ovarian reserve will decrease more substantially.

As to what drives your follicle recruitment rate? The answer here, again, is genetics – a remarkable display of the power that genetics can wield in your health and wellness throughout all your life.

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