There are several methods of calculating the fertile days of a woman’s menstrual cycle. The most popular of them is the so-called Holt’s rule, which calculates fertile days based on the length of the menstrual cycle and the date of the last bleeding. The method assumes 28-day monthly cycles and the occurrence of ovulation (the period when the egg is ready for fertilization) on average in the middle of the cycle, i.e. on the 14th day. With such assumptions, the fertile days are days from the 9th to the 18th day of the cycle (the 1st day of the cycle is the 1st day of menstruation).
Calculating fertile days and contraception
Remember that calculating the fertile days for the purpose of preventing conception (the calendar method) is one of the least effective methods of contraception. This is especially true for girls and young women who have irregular periods.
Enter the date of your last menstrual period and check which week of pregnancy you are ‘
Fertile days calendar
Fertile days calculator