[Knaus' method. The calculation of female fertile and sterile days].

Knauss method for determining periods during which conception is impossible is discussed. Knaus (1892-1970) made his observations in animal studies concurrently with Ogino in Japan. In women with regular menstrual cycles the date of ovulation can be determined from the date of the menstrual period. Generally conception cannot occur during the first 10 days or after ca the 18th day of the menstrual cycle. The method has been shown to have a Pearl index of 2 among more intelligent women and 15-30 in the general population. Ca 25% of all single women and ca 44% of all married women in Germany use this method which is sanctioned by the Catholic church.