As people develop wrinkles and spots on their skin with age, invisible and subtle changes also occur deep in their bodies. Researchers now agree that the aging of women's eggs is an important factor in many reproductive problems, including infertility, miscarriage and birth defects.
In contrast to men, who produce sperm continuously all their lives, a woman produces all her eggs while still in her mother's womb. The eggs are stored in ovaries just before completing reduction division, in which the number of chromosomes are halved, like stock items stored unfinished in a warehouse.
The number of eggs in the ovaries of a female fetus reaches the maximum (as many as 7 million) during gestation. The number declines to 1 million to 2 million at birth and to 300,000 by menarche.