The goal of this study was to analyze female and male factors influencing the fertility of the couple. The projected study aimed at recruiting, through the help of gynecologists, about 500 couples who would not only fill in extremely detailed questionnaires, but would agree to keep exact records of their body temperature for the women, and would agree to 2 sperm examinations for the men. It was obvious from the beginning that the obstacle resided in the required sperm examination, towards which most men had a very negative attitude. When the requirement was erased from the protocol, and the projected study advertised on French newspapers, 857 couples, mostly infertile, offered to participate. Of these 366 dropped from the project, and among the remaining ones 95 pregnancies were registered. The article also reports on 2 similar studies conducted in France and in Thailand.