Diethylstilbestrol as Post-Coital Contraceptive
The administration of large doses of estrogen to women shortly after unprotected, isolated coitus is followed by an extremely low incidence of pregnancy, suggesting an effect of the estrogen in preventing some aspect of early gestation. Controlled studies have not.been carried out, but there would seem to be little doubt of the efficacy of DES while lesser data on EE and other estrogens are suggestive.
The mode-of-action of the estrogens is not well established. Edgren cited the similarity between this human use and the tubal effects in animals (low dose acceleration of egg transport and high dose inhibition, tubal lock, in some species). In contradistinction, Dr. Hertz insisted that the anti-fertility effect in humans resulted from biochemical changes in the endometrium that precluded nidation. The review of Blye mentions both possibilities, as well as others.
The possible danger of this type of therapy, at least with respect to cancer, was disposed of rapidly by the panel. The postcoital use of estrogens, and particularly DES, is high-dose, short term therapy, quite different from the high-dose, long-term approach usually associated with carcinogenesis. Therefore, danger to the woman taking an estrogen correctly would seem minimal. Further, danger for the fetus seems of little significance, even if DES is conclusively proved to be carcinogenic. If pregnancy is prevented, no danger can exist; however, later abortion should be recommended in the event of an unsuccessful termination.
- Are Oral Contraceptives and Diethylstilbestrol (DES) Involved in Sex-Linked Cancer?, Steroid Hormone Action and Cancer, PDF, 5.48 MB, 1976.
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