A progesterone-like substance, usually more active when given by mouth than natural progesterone is. Used with an estrogen in the birth control (oral contraceptive) pill. Commonly used examples have a structure like progesterone itself (e.g. medroxyprogesterone acetate, or Provera; cyproterone acetate, or Androcur) or have a structure distantly related to the male hormone testosterone (e.g. norethisterone, or Primolut N; norgestrel)

Bleeding (usually irregular and light, i.e. 'spotting') while on the birth control pill (the oral contraceptive pill) or while taking a progestogen. With regard to the pill, it is common (and of no sinister importance) in the first few months of pill use; but if it happens after many months' satisfactory use of the pill then it can signal: (1) interference with the efficacy of the pill (i.e. a risk of ovulation and pregnancy) by an illness with diarrhea, simultaneously taking antibiotics, or a drug interaction (taking additional medications that speed up the pill's metabolism; or (2) coexisting pathology of the cervix or the uterus. Unexplained or persistent breakthrough bleeding means you should see your physician.

Latin for yellow body, the description being that of the solid or cystic structure in the ovary after ovulation. Derived from the ovulating Graafian follicle. At first red and friable as arteries and veins invade the collapsed follicle, it soon matures into a gland that is very efficient at producing progesterone, a hormone that's soluble in the fat and which therefore gives the corpus luteum its yellow color. Provides its name to the second, or luteal phase of the ovarian cycle, as well as to luteinising hormone, which causes the corpus luteum to be formed and sustains it until, in the event of pregnancy, it is supported instead by human chorionic gonadotropin. The appearance of the corpus luteum on transvaginal ultrasound is so variable (and so able to be confused with a serious abnormality of the ovary) that for accurate diagnosis of such pathology it is best to scan in the follicular phase or while taking a progestogen to prevent formation of this structure. Plural: corpora lutea.

A progestogen that is particularly effective at blocking the effect of male sex hormones (androgens)on the skin, and therefore reducing abnormal hair growth (hirsutism) and acne. Found singly in Androcur and in combination with an estrogen in Diane-35, a formulation used for oral contraception. Dangerous if taken in pregnancy, because it stops male fetuses from developing normal genital organs. Not available in the US.

A transformation of the lining of the uterus (the endometrium) in pregnancy. Complete confluence of endometrial stromal cells (lying between the endometrial glands) occurs, caused by prolonged (14 days or more) exposure to progesterone or a progestogen; normally happens only with pregnancy.

A formulation of the oral contraceptive pill that contains, as well as an estrogen, the progestogen known as cyproterone acetate, which is particularly effective at blocking the effects of male hormones on the skin. Made by Schering.

(ERT) The therapeutic use of estrogen to stop the effects of menopause after the ovaries have been removed or have stopped functioning. If the uterus is still present the hormone regimen must include at least 11 days' progestogen usage each month, or there will be a risk of endometrial hyperplasia and hence endometrial cancer.

(MPA) A progestogen of a type related to progesterone itself. Marketed as Provera (tablets) and Depo-Provera (injections) by Upjohn.

(NET) A progestogen of a type weakly related to the male hormone testosterone. Progestogens of this class are commonly found in the oral contraceptive pill. Norethisterone acetate is marketed as Primolut N and is made by Schering. Called norethindrone in the US.

A partial confluence of stromal cells of the endometrium (lying between the endometrial glands), caused by prolonged exposure (10 days or more) to progesterone or a progestogen.

(PMT) A distressing group of symptoms usually timed for the lead up to a period, then relieved as menstruation takes place, although many women experience different timing; includes downheartedness or depression (certainly an absence of well-being), aggression, fluid retention and weight gain, painful breasts ('mastalgia'), headaches and pain in the pelvis; caused by a periodic fall in the brain's endorphins, in turn usually precipitated by falling levels of progesterone in the second half of the luteal phase, although similar symptoms often accompany the use of progestogens, especially in older women; may be better during superovulation cycles because of generally higher hormone levels, but this is not always the case and PMT at the end of an unsuccessful cycle of assisted conception is particularly hard to put up with. Usually treated (up to a point) symptomatically, with perhaps fluid tablets (diuretics) and analgesics, although it's claimed that the drug Prozac has a specifically beneficial effect on mood, and encouragement of endorphin release with exercise can also be useful. Because progesterone and progestogens are the culprits, an operation to remove the ovaries (plus hysterectomy to simplify estrogen replacement therapy without needing progestogens) is usually curative, but drastic.

The progestogen norethisterone acetate (UK, Australia) or norethindrone acetate (US) made by Schering.

Strictly, the term progestin encompasses progesterone too (i.e. 'progestins' = 'progesterone' + 'progestogens').

The progestogen medroxyprogesterone acetate, made by Upjohn.