To calculate the fertile period it is necessary to consider that ovulation always happens in the middle of the cycle, that is, around the 14th day of a regular cycle of 28 days.
To identify the fertile period, the woman with a regular 28-day cycle must count 14 days from the date on which the last menstruation came, since ovulation will happen between 3 days before and 3 days after that date, which is what is considered be the woman’s fertile period.
To know your fertile period you can use our online calculator:
First day of your last period:
How many days (on average) your menstrual cycle lasts
How to calculate the fertile period in an irregular cycle
Calculating the fertile period in the irregular cycle is not safe for those who are trying to conceive or for those who do not want to conceive, because as menstruation does not always appear in the same period, the accounts can be wrong.
However, one way to know when the fertile period is in case of irregular cycle is to write down the duration of each menstrual cycle for one year and then subtract 18 days from the shortest cycle and 11 days from the longest cycle.
For example: If your shortest cycle was 22 days and your longest cycle was 28 days, then: 22 – 18 = 4 and 28 – 11 = 17, that is, the fertile period will be between the 4th and 17th days of the cycle.
A more rigorous way of knowing the fertile period in case of irregular cycle for women who wish to become pregnant is to resort to the ovulation test that is bought at the pharmacy and to watch for signs of a fertile period, such as discharge similar to egg white. Check out the 6 main signs of the fertile period .
For women who do not wish to become pregnant, the tablet is not an effective method and, therefore, it is important to use safe contraceptive methods, such as condoms or the contraceptive pil
