What changes in estrogen levels occur during the final years of perimenopause?

During the final one or two years of perimenopause, estrogen levels decline quickly.1

This transition is part of a broader, gradual decline in ovarian function that occurs as a woman approaches menopause. While perimenopause can begin as early as 10 years before the final cessation of menstruation, the specific, rapid drop in estrogen is a hallmark of the final stages of this period. This reduction in estrogen production is a consequence of the depletion of ovarian follicles, which are responsible for secreting the hormone. As these levels fall, it often leads to a disturbed menstrual cycle, characterized by irregular bleeding or missed periods.12