fertility drug, any of a variety of substances used to increase the possibility of conception and successful pregnancy. Different methods are used to correct or circumvent the many different functional disorders of both males and females that can interfere with conception and childbearing (see infertility). The term fertility drug primarily refers to drugs that mimic or stimulate production of a hormone necessary for conception, but it may also be used to refer to the hormones themselves, when they are administered as part of a program of infertility treatment.

The most common cause of female infertility is failure to ovulate. In certain cases this can be corrected with the drug clomiphene citrate (Clomid, Serophene). Introduced in 1967, clomiphene stimulates the release of the gonadotropic hormones: follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH functions to stimulate the ovarian follicle (the egg and its surrounding fluid and hormones); LH triggers ovulation. In some studies, clomiphene has been associated with an increased risk of ovarian cancer. Clomiphene is also used to stimulate spermatogenesis in men with low sperm counts.

Human menopausal gonadotropin, or menotropin (Pergonal), introduced in 1970, is an extract from the urine of menopausal women. It contains FSH and LH and encourages ovulation. It is often given together with human chorionic gonadotropin (HCG), a hormone secreted by the placenta during pregnancy and obtained from the urine of pregnant women. Its action is similar to that of luteinizing hormone. In males the same combination is given to increase testosterone production, which in turn increases sperm production.

Urofollitropin (Metrodin) is essentially follicle-stimulating hormone without luteinizing hormone. It is used especially in women with polycystic ovary syndrome, who tend to have too little FSH and too much LH. A frequent result of ovulation induced by these drugs is the production of more than one ovum (egg) in a month, and subsequent multiple births.

Progesterone is a female sex hormone that induces secretory changes in the lining of the uterus essential for successful implantation of a fertilized egg. It is released by the ovary after the ovum is released. It is administered in cases where fertilization of the ovum does occur but where there is evidence that the uterine lining is unable to support the developing fetus, as in repeated miscarriages or bleeding during pregnancy.

See also DES (diethylstilbestrol).