Progesterone is a hormone that is produced by the corpus luteum in the ovary after ovulation, as well as in the adrenal glands and ovaries in smaller amounts. It plays an important role during menstruation and pregnancy: Progesterone prepares the endometrium of the uterus for pregnancy, making the lining thicker in case a fertilized egg will implant. If there is no fertilized egg, the corpus luteum shrinks again and disappears, causing progesterone levels to fall again. In case of a pregnancy (or by using hormonal birth control), progesterone levels don’t fall, and ovulation does no longer take place.
- Hormone Health Network (Endocrine Society). Progesterone and Progestins. https://www.hormone.org/your-health-and-hormones/glands-and-hormones-a-to-z/hormones/progesterone (accessed 8. August 2020)
- You and Your Hormones (Society for Endocrinology UK). Progesterone. https://www.yourhormones.info/hormones/progesterone/ (accessed 8. August 2020)