How many ovarian follicles normally mature during the reproductive years?

During a woman's active childbearing years—typically between the ages of 13 and 50—only 300 to 400 ovarian follicles normally undergo maturation.1

While the ovaries contain hundreds of thousands of immature follicles at birth, the vast majority of these degenerate over time rather than reaching maturity. At the beginning of each menstrual cycle, several follicles begin to enlarge during the follicular phase, but typically only one or occasionally two are selected to reach full maturity as Graafian follicles before rupturing to release an egg.123