In general, infertile days can be considered all those during which ovulation does not occur. During the infertile days, in the case of unprotected sexual intercourse, the chance of pregnancy is the lowest. It is primarily the menstrual phase itself (during menstrual bleeding), during which sexual intercourse is not recommended. Infertile days are those just before (20th to 28th day) and just after (1st to 7th day) menstruation. However, this is only an assumption in the case of a 28-day cycle, with the ovulation phase starting in the middle of the cycle (10th to 15th day). It is also not true that conception cannot occur during unprotected sexual intercourse outside the ovulation period, because a man's healthy sperm can survive in a woman's body for 3 to 7 days.\r