Is it true that people who experience menstrual periods as early as eight years old run out of eggs earlier than the usual biological clock?
Dear reader,
Firstly, while each ovary contains several million germ cell units (primordial follicles) that reach a maximum of approximately 1.5 million in utero, there is a steady decline in these units throughout the prepubertal and reproductive years. However, menopause does not occur simply because the ovaries are empty. In fact, premature menopause is defined as menopause occurring before the age of 45, affecting around 1 per cent of women under 40 and 0.1 per cent under 30.
Rather, menopause occurs due to a loss of ovarian follicular activity, leading to a decline in oestradiol levels. This hormone is responsible for stimulating the innermost lining of the uterus and triggering ovulation (the release of a mature egg or ovum).
Secondly, the number of eggs in the ovary is not one of the principal causes of premature menopause. Instead, premature menopause is primarily linked to factors such as chromosomal anomalies, hypothyroidism (low thyroid hormone levels), autoimmune diseases (such as Addison’s disease and myasthenia gravis), and enzyme deficiencies.
Why menopause occurs
As the ovaries age, the remaining follicles—likely the least sensitive to reproductive hormones—are increasingly less likely to mature, leading to a decline in ovulation and eventual ovarian failure. The first hormonal change associated with menopause is a reduction in inhibin production by the ovary. Inhibin is responsible for regulating follicle-stimulating hormone (FSH) production from the pituitary gland. When inhibin levels drop, FSH levels begin to rise uncontrollably. Eventually, oestradiol production becomes insufficient to stimulate endometrial proliferation, and menopause ensues.
