THE EFFECTS OF SEVERAL STEROIDS ON FECUNDITY IN FEMALE RATS

Abstract

Female rats were treated with steroids daily from 5 days before to 30 days after placing with males. At the higher dose levels no pregnancies were observed during the treatment period. On a weight basis, estrone and Vallestril were the most potent; norethynodrel and testosterone propionate were somewhat less active. Progesterone was least effective of the compounds studied. Nilevar, which has both anabolic and progestational activities, was nearly as effective as testosterone propionate in preventing pregnancy. 17[alpha]-(l-methallyl)- and 17[alpha]-(2-methallyl)-19-nortestosterone, both of which are potent progestins in the Clauberg assay, were also more effective than progesterone in preventing pregnancy in rats.