The answer lies in the wording of the question. More precisely, it is essentially impossible for a woman to get pregnant during her period, but on rare occasions it is possible for a woman to get pregnant from intercourse during her period. Since sperm can live for five days, a couple could have sex near the end of the woman’s period, and the sperm could then live long enough to fertilize an egg several days later, if the woman had a very early ovulation. (Conception is more likely in these cases if intercourse occurs at the end of a 6- or 7-day menstruation.) It’s also possible that women who think they got pregnant from intercourse during their period were actually having sex during ovulatory spotting.