A vital female sex hormone necessary for the proper operation of the female reproductive system. Progesterone is synthesized in the ovaries during the latter part of the menstrual cycle and by the placenta during pregnancy. Minimal quantities are also generated by the adrenal glands and, in males, by the testes.
Throughout the menstrual cycle, progesterone levels rise post-ovulation (the discharge of an egg from an ovary), prompting the endometrium (lining of the uterus) to thicken, priming it to receive a fertilized egg. Should fertilization not transpire, the production of progesterone and estrogen hormones decreases to a point where a menstrual period ensues, expelling the uterine lining from the body.
When pregnancy transpires, the placenta generates progesterone, leading to several alterations in the mother’s physique, including breast enlargement. A decline in the mother’s progesterone levels toward the end of pregnancy plays a role in triggering labor.
Progesterone also brings about effects in women such as elevated fat storage and heightened sebum production by skin glands.