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Where does progesterone come from?

Elena H. Yanushpolsky, MD
OBGYN (Obstetrics & Gynecology)

Progesterone is a hormone that is secreted by the ovary after ovulation. During the first two weeks of the menstrual cycle, the growing egg is surrounded by granulosa cell. During that time, up until ovulation, granulose cells mainly secrete the hormone estrogen.  Once ovulation takes place and the egg is released from the ovary, granulosa cells change their secretion pattern and begin to secrete progesterone in addition to estrogen. The part of the ovary that secretes estrogen and progesterone after ovulation is called Corpus Luteum. Progesterone is important for preparing the uterine lining to receive a fertilized egg and for supporting early pregnancy. As pregnancy continues successfully and placental cells grow, they take over production of progesterone, and corpus luteum gradually involutes by 8-12 weeks of pregnancy. The placenta continues to produce large quantities of progesterone throughout pregnancy.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.