Perimenopause, a term meaning “around menopause,” is the transitional period leading up to the final menstrual period. This phase can begin eight to ten years before menopause, often starting when an individual is in their 40s, and is characterized by fluctuating levels of key hormones like estrogen and progesterone. During this time, the ovaries gradually produce less estrogen, which leads to the first signs of change, such as irregular periods, even while menstruation continues. The duration of perimenopause varies greatly among individuals, lasting an average of four years but potentially extending for up to a decade for some. This process officially concludes once a person has gone 12 consecutive months without a period.