Understanding the Ovarian Clock – Essential Knowledge for Paediatricians

A woman is born with her life-time supply of eggs, and these are surrounded by a group of cells, the follicular cells, which formed the ovarian follicles. The ovarian follicles will determine a woman’s entire reproductive lifespan and healthspan. The ovarian follicles are at their peak numbers in utero and start to decline in numbers upon birth and a non-linear decline throughout a girl’s growing up, reaching adolescence and adulthood. This decline also represents the inevitable loss of fertility, culminating in the menopause in women, where the ovaries have too few ovarian follicles left to result in monthly menstrual bleeding. The role of these ovarian follicles is vital for a woman’s fertility due to the eggs which they protect. Importantly, the hormones secreted by the ovarian follicles, e.g., estradiol, maintain a woman’s healthspan by ensuring optimal cardiovascular, musculoskeletal, and neurocognitive health.