Yes, she can if SHE wants too. If she and her partner are willing there is nothing to stop them having sexual relations at this time. In some cultures it is taboo, something about the menstrual blood draining their manhood. Personally I think a smart woman invented that one to give her a period (pardon the pun) of respite from sex. If she uses tampons during her cycle she may need to use a lubricant as there will be little natural moisture and that can be painful. If her heaviest days are the first two then it might be better to wait til a little later in the cycle. No, you can't get pregnant at this time, (Unless your cycle is under 17 days - you ovulate 14 days before your next period) but still use protection, periods don't offer any protection against S.T.D.'s. Hope this helps, B