The answer to this question is somewhat tricky. The general answer is that most women are fertile for only a few days per cycle. However, there are several factors to consider:

1. The woman’s egg can only live up to 24 hours. Two or more eggs may be released over a maximum of 24 hours. So, in a vacuum, a woman is only fertile for about a day or two. But the man’s sperm 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 as long as she has fertile quality cervical fluid, up through ovulation. That might be several days, or as few as one.
3. For a couple trying to prevent pregnancy, FAM adds a buffer zone of a few days to assure that an unplanned pregnancy does not occur. This usually results in about 7-10 days being considered fertile per cycle.