The Reproductive Life Cycle
There are five reproductive stages in a woman’s reproductive life cycle. These include premenarche (before the first menstrual period) stage; the reproductive, premenopausal stage; the early menopausal transition stage; the late menopausal transition stage; and finally, menopause. There is no single test to determine reproductive potential, but the menstrual cycle pattern and hormone levels can give rough estimates.
The reproductive, premenopausal stage is characterized by regular menstrual cycles and FSH hormone levels generally less than 10 mIU/mL on menstrual cycle days 2,3, or 4. Other measurable parameters that are proposed to be predictive of ovarian reserve and potential fertility include: ovarian, antral, follicle count; antimullerian hormone (AMA) levels greater than 0.3 ng/mL; and a Clomiphene citrate challenge test.
The early menopausal transition stage commonly begins 7 to 8 years prior to menopause and is characterized by increased menstrual cycle variability usually shortening of the time between menstrual periods. FSH hormone levels are often greater than 10 mIU/mL and AMH levels are less than 0.4 ng/mL.
The late menopausal transition stage occurs 3 to 4 years prior to the final menstrual period. This begins when 2 or more menstrual cycles are missed or more than 60 days elapses between periods. FSH levels are generally greater than 30 mIU/mL and early follicular (cycle days 2-4) estrogen levels are over 100 pg/mL. AMH levels are usually below assay sensitivity.
The last stage of a woman’s reproductive life cycle is menopause. Menopause is defined as 12 months without a menstrual period and is often but not always associated with hot flashes, night sweats, and signs of estrogen deficiency including vaginal dryness, breast shrinkage, and urinary difficulty. FSH and LH hormone levels are greater than 40 mIU/mL and estrogen levels are often undetectable.
The average age of menopause is 51. Anytime before age 40 is considered abnormal. A woman’s mother’s age at menopause often predicts when she will go through menopause. The earlier the mother experiences menopause, the poorer the ovarian reserve in the daughter after age 35. Smoking, prior ovarian surgery, and severe endometriosis can affect ovarian reserve and is associated with decreased fertility and earlier menopause.