The term “Fertile Window” refers to the time period during which conception can occur. When the oocyte is released by the ovary during ovulation, it remains in the Fallopian tube waiting to meet the spermatozoon for approximately 12 hours.

The fertile window begins approximately 4 days before the process of ovulation, as the spermatozoa, after ejaculation during sexual contact, can fertilize the oocyte when the sperm is characterized by normal parameters (concentration, motility, morphology).

The following question emerges: which days are fertile during the menstrual cycle?

The answer to this question is not the same for all women of reproductive age. In women who have regular cycle, ovulation occurs 14 days before their next period. Essentially, this means that when a woman has a 28-day menstrual cycle, ovulation occurs on the 14th day of the cycle, whereas in case of a woman with a 27 or 26-day-cycle, ovulation takes place on the 13th or 12th day, respectively. If a woman has a short, 24-day cycle, the ovulation occurs on the 10th day of the cycle; accordingly, in case of women with   long, 35-day cycle, ovulation happens on the 21st day.

It’s clear from the above that when a woman is interested in getting pregnant, she should write down the dates of her monthly menstruation in order to be able to estimate the ovulation time and, therefore, her fertile window, which begins approximately 4 days before the ovulation.