Progesterone is a type of hormone that belongs to the progestogen family. Progesterone is largely responsible for initiating and maintaining the cycle of ovulation or fertilization in a woman's body. During the second half of a woman's cycle, the corpus luteum, an endocrine gland, secretes progesterone. Supplementing with a progesterone replacement is common among women with low levels, but there are a few side effects to be aware of.
Progesterone prepares the female body for fertilization of the egg after ovulation. It thickens the endometrium lining to accept the fertilized egg. Progesterone also tones down muscle contractions so that the uterus doesn't reject the egg. If the egg isn't fertilized, the progesterone levels drop, initiating a new menstrual cycle. If the body conceives, the progesterone stimulates the body to provide endometrium with red blood vessels. This helps in fetus development.
Once the placenta develops, it starts releasing progesterone as well. This maintains consistent levels of progesterone in order to avoid further egg production. Progesterone also causes milk production in the breasts. If progesterone and estrogen are combined in the form of a pill, it serves as an excellent birth control contraceptive. Progesterone also treats menopausal symptoms in women's bodies, and normal side effects usually subside naturally.