Clomiphene, a compound that is frequently referred to as a "fertility pill", is a
drug that has affinity for and binds to
estrogen receptors in the
hypothalamus but is devoid of
intrinsic activity. Clomiphene has enabled many women who were previously unable to
conceive to become
pregnant. The drug has also been responsible for causing
multiple births; sometimes four or five
ova are released and
fertilized in women who take the drug. However, the possibility of bearing more than one child is usually not considered a problem for
couples who have not been able to conceive by other methods. Because clomiphene acts on the hypothalamus, the
pituitary gland and
ovaries must be functional if the drug is to improve a woman's chances of
conception. Thus, the drug is ineffective (of course) if
infertility is caused by a deficit in the man, or when the woman's infertility is caused by pituitary or ovarian
dysfunction.
Ordinarily the administration of clomiphene is started on day 5 of the menstrual period; it is then taken daily for 5 days. The drug is than stopped until the next menstrual cycle if the woman does not become pregnant. The procedure is then repeated, often with slowly increasing doses. Approximately 35% of formerly infertile women become pregnant when they take clomiphene. Side effects include ovarian cysts (14%), multiple pregnancies (8%), and birth defects (2%). (The incidence of birth defects in nontreated women who conceive without the aid of clomiphene is approximately 1%.)