Potencies of oral contraceptives. Letter.

This letter is a response to the discussion by Edgren and Sturtevant (125:1029 1976) on potencies of oral contraceptives (OCs). It is agreed that the results of studies in animal models on OC potencies may not necessarily reflect true potencies in human subjects however these animal models do allow the evaluation of the biological effects and interactions of the components of OCs. Data obtained in animal studies are acknowledged to be valuable aids in the study of human diseases. Likewise mouse uterine response to contraceptive steroids is 1 criterion to be used in evaluating steroid potency. As previously reported the importance of the mouse uterine response is that the contribution of the progestin component to the total estrogenic potency of the OC is demonstrated.