The menopause is defined as the permanent cessation of menstruation (periods). The average age range for women going through the menopause is 45-55 years with the average age being 51 years. Age 40-45 is considered an early menopause and under 40 is considered a very early menopause or premature ovarian insufficiency. Conversely, some women can have periods until their late 50s.
In the lead-up to the menopause, women’s ovaries no longer respond to hormones from the pituitary gland in the brain, and therefore no longer release an egg as the main hormones produced by the ovary (oestrogen, progesterone and testosterone) begin to fall, which will eventually lead to cessation of periods. Menopause has occurred if there has been no period after 12 consecutive months for women aged 50 years or older, where no other cause can be identified. For women under 50 years, it’s 24 consecutive months.
Due to fluctuations in hormone levels around the perimenopause and early menopause, blood tests don’t “determine” menopause and it can only be defined with certainty 1-2 years after cessation of periods depending on age. However, a surgical menopause due to removal of ovaries is different in that it causes an immediate menopause.