Many women who have high FSH are told by their doctors that they are in menopause. This is a very alarming thing to hear, especially for a young woman trying to get pregnant. Many doctors indicate that a a patient is “in menopause” solely based on their FSH. In actuality, the entry to menopause is much more complex and subtle than any one test can indicate.
There was an excellent article on Medline that I have summarized below. You can also refer to this article for some interesting technical details. My summary is as follows:
- The phases of fertility are referred to as “reproductive years”, “menopausal transition” and “menopause”.
- The reproductive years are subdivided into “early”, “peak” and “late”. The early and peak reproductive years are characterized by high fertility and regular cycles. The late reproductive years are characterized by somewhat declining fertility and regular cycles. FSH levels can either be normal or elevated during the late reproductive years. Sometime in the late reproductive years – generally ten to fifteen years before menopause, the length of the menstrual cycle decreases (due to a shortened follicular phase).
- Menopausal transition lasts on average around 4 to 5 years, but can be 0 years or up to 10 years in duration. Menopausal transition is also known as perimenopause, although perimenopause is technically different from menopausal transition in that perimenopause also includes the first year after menses have ceased. Menopausal transition has two phases known as “early” and “late”. The early menopausal transition is characterized by variable cycle length (variation of more than 7 days from normal cycle length) and late menopausal transition is characterized by two or more skipped cycles and an interval of amenorrhea (of 60 days or longer). The average cycle length and the standard deviation of cycle length begin to increase and ovulation occurs less frequently. Fertility begins to decline in the late reproductive years, declines further in the early menopausal transition and further still in the late menopausal transition.
- Menopause is defined as the permanent cessation of menses. Menopause occurs at a mean age of around 51, with a standard deviation of around 2 years. Menopause is said to be “natural” if it occurs at or after the age of 40 and is said to be “premature” if it occurs prior to the age of 40. Premature menopause is also known as premature ovarian failure (POF). FSH is constantly elevated in menopause, although studies that have attempted to define a specific cutoff on FSH to define menopause are inconclusive.
So, it seems that this gradual progression from peak fertility to menopause can take several years. High FSH might be an indicator that a person is somewhere on this progression but not necessarily in menopause. The key to understanding a woman’s chances for pregnancy is to try to determine where on the progression she is. The earlier in the progression, the higher the chance for pregnancy.