Eggs (oocytes) 

Ovulation is the release of a mature egg from the woman’s ovary and is a critical part of the reproductive process.

Women are born with their lifetime supply of eggs: they don’t produce new eggs and as they age the supply of eggs in their ovaries decreases. The rate of loss of eggs varies between women. It can be difficult to predict the amount of eggs and level of fertility a woman has as she ages.

Polycystic Ovarian Syndrome (PCOS) is a condition typically found in women who don't ovulate. For the diagnosis to be made women have to have two out of the following three criteria:

• polycystic ovaries on ultrasound (more than 12 follicles per ovary)
• irregular or absent periods
• excessive male hormone production (causing acne and/or excessive hair growth)

Women may have polycystic ovaries, but none of the other symptoms. These women do not have PCOS.