According to WebMD, it is possible for a woman to get pregnant while on her period. However, experts conclude that it is not very likely for this to happen. For a woman to get pregnant on her period, she would have to have intercourse near the end of her period and ovulate a few days later. Since sperm can live up to five days, women can technically become pregnant.
As described by WebMD, another possibility for a woman who thinks she may have become pregnant during her period is that the woman mistakes bleeding that occurs in between periods for her period. Ovulation, which occurs mid-cycle, can sometimes cause bleeding that can be mistaken for a period. Woman that actually do conceive during their periods usually do not have regular menstrual cycles of 28 to 32 days, according to Jennifer Barton. Barton describes an example of a woman with a 24-day period. If that woman bleeds for seven days and has intercourse on the final day of her period, she could ovulate three days later. If the sperm have survived for those three days, that woman could become pregnant. Barton advises women to watch out for early pregnancy symptoms including cramping, spotting, tenderness in breasts and moodiness.