Under normal circumstances, about 10 follicles are “at the starting line” of each menstrual cycle. However, the number varies significantly based on a woman’s age and ovarian reserve, typically ranging from 1 to 30 follicles. Naturally, after about 14 days, due to the body’s limited gonadotropin supply, only one follicle reaches maturity and ovulates, while the rest are lost through a process known as atresia in medical terms.

Ovarian stimulation works by using additional gonadotropins to allow follicles that would otherwise undergo atresia to mature and reach ovulation. These mature follicles are then retrieved for in vitro fertilization (IVF). Importantly, the gonadotropins used in ovarian stimulation do not affect smaller follicles from subsequent cycles, as these follicles lack receptors for the hormones at this stage.

Thus, ovarian stimulation is a process of turning “waste into treasure” by maturing follicles that would otherwise have been lost, without depleting future ovarian reserves or causing premature aging.