menopause

thumb|right|Тhe changes in ovarian hormones throughout the human lifespan. During childhood, hormone levels are low. During puberty, estrogen begins to fluctuate, followed by progesterone when you first begin ovulating. After 6-12 years the menstrual cycle normalizes into a rhythm during the menstrual years, barring any reproductive health issues or pregnancy and breastfeeding, which pauses the cycling. Perimenopause, similar to puberty, has high fluctuations of estrogen as progesterone slowly begins to decline. Eventually, a person stops ovulating, reaches menopause, and hormones return to childlike levels with low progesterone.

Menopause is the time when menstrual periods permanently stop, marking the end of the reproductive stage for the female human. It typically occurs between the ages of 45 and 55, although the exact timing can vary. Menopause is usually a natural change related to a decrease in circulating blood estrogen levels. It can occur earlier in those who smoke tobacco. Other causes include surgery that removes both ovaries, some types of chemotherapy, or anything that leads to a decrease in hormone levels. At the physiological level, menopause happens because of a decrease in the ovaries' production of the hormones estrogen and progesterone. While typically not needed, measuring hormone levels in the blood or urine can confirm a diagnosis. Menopause is the opposite of menarche, the time when periods start.