During the presidency of Belaunde, the Catholic Church’s stance on family planning mirrored that of Pope Pius XI’s encyclical Casti Connubii .  The Pope declared that parents should responsibly control their fertility so as to have only the number of children they can care for while respecting life at conception. 

Dr. Joseph Kerrins was an obstetrician and member of the Christian Family Movement from the United States who came to Peru in 1966.  Here he observed in a letter to Cardinal Juan Landazuri, “there seemed to be no doubt in their minds they wanted me to help them to stop having so many babies.”  Dr. Kerrins decided to work with the Sons of Mary Parish to create a program of family planning that abided by the ideals of the Catholic Church; it was called the Responsible Parenthood Program in the Barriadas of Lima.  This program provided full gynecological services in a clinic within the parish.  The clinic also distributed contraceptive pills provided by the CEPD for up to 2 years with information sessions on periodic abstinence.  The idea was for women regulate their menstrual cycles in order to effectively utilize the catholic church approved methods. 

The program was so successful, that it began spreading to other perishes in 1967.