It is possible to be pregnant and to experience vaginal bleeding. This type of bleeding, however, would not be attributed to a menstrual period (menstruation). Vaginal bleeding during pregnancy especially if followed by abdominal cramps should be taken very seriously because it could be a sign of a miscarriage. Weak vaginal bleeding that corresponds with the normal menstrual period date could be present in the first months of pregnancy, but it does not usually indicate illness or disorder.