Ovaries – The true beginning of a woman’s reproductive lifespan and healthspan

Ovaries – The true beginning of a woman’s reproductive lifespan and healthspan The ovaries play a significant role in a female’s overall reproductive health, which can affect susceptibility to age-related conditions. Dr. Paula Benny and Adjunct Assistant Professor Zhongwei Huang from the NUS Bia-Echo Asia Centre for Reproductive Longevity and Equality discuss the factors influencing reproductive lifespan and healthspan. Each baby girl is born with her lifetime supply of eggs, which are surrounded by a layer of follicular cells nurturing the eggs’ growth and development. (1) The flattened layer of follicular cells surrounding the egg is known as the primordial follicle. This pool of primordial follicles will form the true ovarian reserve a girl will ever possess in her lifetime. In women, all primordial follicles are formed in the fetus between six and nine months of gestation. During this period, a marked loss of oocytes occurs due to apoptosis, until approximately 1-2 million ovarian follicles are left at birth. The number of primordial follicles decreases progressively because of their recruitment during ovarian folliculogenesis, where they grow and develop, but only one will be selected for ovulation each month for reproductive purposes. This happens until there are 1000 primordial follicles or less, and culminates as the clinical menopause. The decline in the number of ovarian follicles is not linear throughout a girl’s lifetime, with optimal fertility occurring during 18 to 31 years of age. This is then followed by a steep decline in the quantity and quality of ovarian follicles from 37 years of age and beyond, leading to fertility loss. Eventually, with the complete spontaneous cessation of menstrual cycles occurring at approximately 50 years of age, due to the clinical menopause, this marks the end of a woman’s reproductive lifespan and the deterioration of healthspan.