Following extensive examination of published and unpublished materials, we provide a history of the use of dexamethasone in pregnant women at risk of carrying a female fetus affected by congenital adrenal hyperplasia (CAH). This intervention has been aimed at preventing development of ambiguous genitalia, the urogenital sinus, tomboyism, and lesbianism. We map out ethical problems in this history, including: misleading promotion to physicians and CAH-affected families; de facto experimentation without the necessary protections of approved research; troubling parallels to the history (...) of prenatal use of diethylstilbestrol (DES); and the use of medicine and public monies to attempt prevention of benign behavioral sex variations. Critical attention is directed at recent investigations by the U.S. Food and Drug Administration (FDA) and Office of Human Research Protections (OHRP); we argue that the weak and unsupported conclusions of these investigations indicate major gaps in the systems meant to protect subjects of high-risk medical research. (shrink)