You would think that this would be a fairly straightforward question, right? In reality, it’s not that simple. And to add more intrigue, the answer depends on whether you are trying to get pregnant or avoid pregnancy. What? While it’s true that the basic answer is that most women are fertile for only a few days per cycle, there are several factors to consider:
1. The woman’s egg can only live up to 24 hours. And two or more eggs may be released within 24 hours. So, in a vacuum, a woman is fertile for only about a day or two. (Of course, if a woman is trying to get pregnant inside a Hoover, she’s probably got bigger issues to deal with than when she is fertile.) The man’s sperm, on the other hand, can live up to 5 days, so the combined fertility of the two individuals is about a week.
2. For a couple trying to get pregnant, the woman’s fertile phase is only as long as the number of days she has fertile-quality cervical fluid preceding ovulation, since this is what allows the sperm to travel through the cervix to reach the egg. That might be several days, or even just a few hours.
3. For a couple trying to avoid pregnancy, though, the Fertility Awareness Method adds a buffer zone of a few days on both sides of her fertile phase to assure that an unplanned pregnancy cannot occur. This usually amounts to about 8 to 10 days per cycle in which she would need to consider herself potentially fertile.
So the next time you’re at a party and the perennial fertile phase question comes up, you can impress those gathered around by telling them it depends on why they want to know.