The fertile window.

Body and Cycle

The fertile window.

The female menstrual cycle is a fascinating, yet complex affair. It is divided into different phases, which in turn are controlled by different hormones and other factors. The question of how long a woman’s fertility phase lasts over the course of a cycle is asked frequently. But how much of a mystery is it?


Is a woman, as many people claim, only fertile one day in her cycle? Or does the fertile phase last two or even five days? Now, what is in fact true?


Technically, the ovum can only be fertilised for up to 24 hours after it is released into the fallopian tube. Once ovulation has taken place, fertilisation can only take place within this time window. This is why it is so important to be able to estimate the time of ovulation, because strictly speaking, a woman is only fertile at this precise moment.


Nature has planned in a certain leeway for getting pregnant so that you don’t have to feel like Kiefer Sutherland in the TV series ’24’ . Since sperm can survive up to five days in the uterus, the fertility window is therefore extended to six days.


In other words, the five days before ovulation (due to sperm viability) and the day of ovulation (due to egg cell viability) are defined as the fertile days of the woman. Unprotected sexual intercourse during this period is significantly more likely to lead to conception, than on any other day of the female cycle.

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