progesterone

Examples of progesterone in the following topics:

• Extrauterine Effects of Estrogens and Progesterone

  • Progesterone exerts its primary action through the intracellular progesterone receptor, although a distinct, membrane-bound progesterone receptor has also been postulated.
  • If pregnancy does not occur, progesterone levels will decrease, leading to menstruation.
  • Normal menstrual bleeding is progesterone-withdrawal bleeding.
  • In addition, progesterone inhibits lactation during pregnancy.
  • The fetus metabolizes placental progesterone in the production of adrenal steroids.

• Hormonal Methods

  • progesterone-only methods which contain only progesterone or one of its synthetic analogues.
  • For example, breakthrough bleeding is much more common with progesterone only methods.
  • The mechanism of action of progesterone-only contraceptives depends on the progesterone activity and dose.
  • Low dose progesterone-only contraceptives include traditional progesterone-only pills, the subdermal implant Jadelle, and the intrauterine system Mirena.
  • The same cervical mucus changes occur as with low dose progesterone.

• Female Hormones

  • Estradiol and progesterone are steroid hormones that prepare the body for pregnancy.
  • Progesterone assists in endometrial re-growth and inhibition of FSH and LH release .
  • As the follicles grow, they begin releasing estrogens and a low level of progesterone.
  • Progesterone maintains the endometrium, the lining of the uterus, to help ensure pregnancy.
  • The endometrium begins to degenerate as the progesterone levels drop, initiating the next menstrual cycle.

• Pineal Gland and Gonads

  • The ovaries produce hormones, such as estrogen and progesterone, which cause secondary sex characteristics and prepare the body for childbirth.
  • Estrogen and progesterone are responsible for the development of the breast and for the uterine cycle.
  • Progesterone is a female hormone secreted by the corpus luteum after ovulation during the second half of the menstrual cycle.
  • In the event of pregnancy, the progesterone level remains stable beginning a week or so after conception .
  • Male testes produce androgens, while female ovaries produce estrogen and progesterone.

• Ovaries

  • Ovaries secrete both estrogen and progesterone.
  • Progesterone functions with estrogen by promoting menstrual cycle changes in the endometrium.
  • Ovaries secrete estrogen, progesterone, and testosterone. 
  • Progesterone prepares the uterus for pregnancy and the mammary glands for lactation.
  • The co-actions of progesterone and estrogen promote menstrual cycle changes in the endometrium.

• Hormonal Regulation of the Female Reproductive Cycle

  • The menstrual cycle is controlled by a series of changes in hormone levels, primarily estrogen and progesterone.
  • This also causes endometrial cells to produce receptors for progesterone, which helps prime the endometrium to the late proliferative phase and the luteal phase.
  • The main hormone associated with this stage is progesterone, which is produced by the growing corpus luteum and is significantly higher during the luteal phase than other phases of the cycle.
  • Progesterone plays a vital role in making the endometrium receptive to implantation of the blastocyst and supportive of the early pregnancy.
  • The death of the corpus luteum results in falling levels of progesterone and estrogen, which triggers the end of the luteal phase.

• Uterine (Menstrual) Cycle

  • After ovulation, under the influence of progesterone, the endometrium changes to a secretory lining in preparation for the potential implantation of an embryo to establish a pregnancy.
  • If implantation does not occur within approximately two weeks, the progesterone-producing corpus luteum in the ovary will recede, causing sharp drops in levels of both progesterone and estrogen.
  • High estrogen and progesterone levels stimulate increased endometrial thickness, but following their decline from a lack of implantation, the endometrium is shed and menstruation occurs.

• Ovarian Cycle

  • The main hormone associated with this stage is progesterone, which is significantly higher during the luteal phase than in other phases of the cycle.
  • It continues to grow for some time after ovulation and produces significant amounts of hormones, particularly progesterone, and to a lesser extent, estrogen.
  • Progesterone plays a vital role in making the endometrium receptive to implantation of the blastocyst and supportive of the early pregnancy.
  • The death of the corpus luteum results in falling levels of progesterone and estrogen.
  • Continued drops in estrogen and progesterone levels trigger the end of the luteal phase, menstruation, and the beginning of the next cycle.

• Placenta

  • hCG also ensures that the corpus luteum continues to secrete progesterone and estrogen.
  • Progesterone is very important during pregnancy because, when its secretion decreases, the endometrial lining will slough off and pregnancy will be lost. hCG suppresses the maternal immunologic response so the placenta is not rejected.
  • Progesterone is necessary to maintain the endometrial lining of the uterus during pregnancy.
  • Levels of progesterone are high during pregnancy.

• Intrauterine Devices (IUDs)

  • Among modern IUDs, the two types available are copper-containing devices, and a hormone-containing device that releases progesterone.
  • Although use of the Mirena results in much lower systemic progestogen levels than other very-low-dose progestogen-only hormonal contraceptives, it may still have some of the same side effects as low does progesterone-only hormonal contraceptives.
  • First introduced in 1990, it releases levonorgestrel (a progesterone) and may be used for five years.