Bishop Gerald Shaughnessy of Seattle suppressed the "rhythm method" device & pamphlet in his territory as stated in this letter from March 15th, 1935. The letter also refers to the "propaganda with regard to the rhythm theory" which is countered by "the decision of the Sacred Penitentiary of 6 June 1880." The Sacred Penitentiary then ruled that [NFP] may not be used to avoid "having numerous children."
Also prohibiting the "notorious and malodorous rhythm system" info was Archbishop Murray of St. Paul, MN in this 1940 letter. Culture of death cannot become culture of life with the passage of time.