This fall is associated with hot flashes, a higher risk for cardiac disease, and an increase of bone loss. Progesterone Progesterone is a steroid hormone synthesized by the corpus luteum. Progesterone stimulates the cyclic changes in the uterine endometrium that allows the implantation of the fertilized egg. It is also responsible for maintenance of the uterus during pregnancy, suppression of uterine contractions, and preparation of the breasts for lactation. Progesterone levels are low during the follicular phase.
Levels increase sharply for a maximum of ten days following ovulation.
Levels decline rapidly at about 4 days prior to menstruation. Testosterone Testosterone is a steroid hormone synthesized primarily by the testes in males, the ovaries in females, and adrenal glands of both sexes. Testosterone is synthesized from androstenedione, a metabolite of DHEA and progesterone, the precursors of which are pregnenolone and cholesterol. From puberty through the reproductive years, males synthesize 20 times more testosterone than females. In males, testosterone is utilized to develop the external genitalia, secondary hair patterns, stimulation of spermatogenesis, development of muscle mass, and behavioral patterns.