Description of the study population. Description of the study population, among couples living in Beaumont-Hague and in the Saint-Brieuc area, France: pregnancies that led to a live birth or a spontaneous abortion; pregnancies that occurred while the couple was using or was not using a contraceptive method. Periods of involuntary infertility lasting 12 months or more, and not leading to a pregnancy whatever the outcome. * Restricted to the periods of unprotected intercourse started between the 1st of January 1985 and the 31th of July 1999. † The current partner answered the questionnaire and was the partner of the woman at the beginning of the period of unprotected intercourse. Two men (3 observations) with radiotherapy for cancer before the beginning of the unprotected intercourse were excluded. ‡ Eight couples (9 observations) who declared less than 4 unprotected intercourse per month were excluded.