Perimenopause refers to the time before menopause, that is, before a woman stops menstruating completely.
Estrogen levels decrease during perimenopause. The levels gradually decline until a woman stops menstruating. Until then, a woman is in perimenopause. Perimenopause is also called premenopause. Egg production by the ovaries is falling, and estrogen is also diminishing. The production of progesterone also lessens, especially if a woman is no longer ovulating. These hormonal fluctuations vary from woman to woman. Both the amount of hormone produced and the timing of the decline can vary.
As women get closer to menopause, the risks of osteoporosis, or bone thinning, and heart disease increase. Lower estrogen levels may be part of the reason that these risks increase.