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January 22, 1938


Author Affiliations


From Northwestern University Medical School and Michael Reese Hospital.

JAMA. 1938;110(4):257-261. doi:10.1001/jama.1938.02790040011003

In spite of the fact that scientific proof of the validity of the fertility-sterility rhythm in woman is incomplete, the method of periodic continence presented a welcome alternative for the objectionable birth control methods. Complete confidence in the efficacy of the safe period principle, however, is not shared by all.

The theory of a fertility-sterility rhythm presupposes that in the sex cycle of woman there is a sterile or "safe period." This is based on the conception of regular menstruation with a fixed or estimable time of ovulation which can be readily reduced to a workable plan for the average woman. In arriving at this rhythmic principle three important factors are considered as basic; namely, (1) the phenomenon of ovulation and the time of its occurrence in woman, (2) the life span and fertilizability of the ovum and (3) the rôle of the spermatozoon.

In order to establish the exact