Physicians' sources of information about teratogenic effects of drugs.

Physicians are frequently called upon to prescribe or give advice about drugs used during pregnancy. Many of these drugs are used effectively and without complications while others may adversely affect prenatal development. Information about risks, however, is scanty, not critically reviewed, and dispersed in the literature, seldom providing clinically useful information. The inadequacy of literature sources results partiaUy because of moral and legal considerations regarding research with pregnant women. Study of drug effects by conventional, prospective, double-blind techniques cannot be performed; therefore, alternative and less satisfactory study methods are employed. Animal studies cannot always be extrapolated to humans. Large scale retrospective studies often have numerous shortcomings including exposure to multiple drugs, the occurrence of confounding diseases, and incomplete or inacurate exposure data. Anecdotal case reports lack the controls necessary to establish causality and may, therefore, represent coincidental drug exposure in a child with a malformation produced by other causes. Thus, by dcfault, manufacturers must use the disclaiming statement, “Safety of the use of this drug during pregnancy has not