Progesterone is a female sex hormone that plays an important role in the menstrual cycle and maintaining pregnancy. The body produces this hormone mainly in: 1) the ovaries, particularly by the corpus luteum after ovulation, 2) the adrenal glands in small amounts, and 3) the placenta during pregnancy.

Main Functions of Progesterone

1. Menstrual cycle – Progesterone prepares the uterine lining to receive a fertilized egg. If pregnancy does not occur, progesterone levels drop, causing the uterine lining to shed and menstruation to begin.
2. Pregnancy – During pregnancy, progesterone helps maintain the uterine lining and support fetal development. It also reduces uterine contractions, helping to prevent premature labor.
3. Mammary glands – Progesterone stimulates the development of breast tissue and prepares it for milk production during breastfeeding.
4. Hormonal balance – Progesterone also acts as an antagonist to other hormones, such as estrogen, helping maintain hormonal balance in the body.

Progesterone is also used in medicine to treat various conditions, including hormonal imbalances, menstrual cycle problems, and the relief of menopausal symptoms. It is often administered as part of hormone replacement therapy (HRT) for some women, to reduce the risk of estrogen-induced thickening of the uterine lining and potential endometrial cancer.