Developer's DescriptionBy ZANA digitalDetermine infertile days in the female cycle.Natural family planning program to determine up to 12,5 infertile days in the female cycle, next menstruation, the likely ovulation and forecast accuracy on a user friendly basis. For women from 18 to 45 years of age - freeware (a modern version is available online at www.natuerliche-verhuetung.de).