Progesterone

Progesterone is a hormone produced primarily by the ovaries, explicitly after ovulation each month. During a woman’s reproductive years, it plays a critical role in regulating her menstrual cycle and supporting pregnancy. It also helps balance the effects of estrogen in your uterus, which is why it plays a vital role in hormone therapy for women who still have a uterus.

During perimenopause, ovulation becomes irregular and progesterone levels start to decrease before estrogen does. This is why heavy periods and irregular cycles are often some of the first symptoms women notice. Micronized progesterone (a form of progesterone that is chemically identical to the progesterone your body makes) is commonly used in hormone therapy and is generally well tolerated.