Any slight to profuse bleeding between menstrual periods. The most common causes of abnormal bleeding are stress or hormonal changes; more serious causes include fibroid tumors, growths in the uterus, liver disease, congestive heart failure, high doses of anti-coagulants, aspirin. An occasional minor spotting midway through the menstrual cycle during ovulation is rarely serious; bleeding accompanied by fever, pain, and/or other discharge may indicate an infection that should be treated immediately before more serious complications set in; bleeding during pregnancy may be a forewarning sign of miscarriage; bleeding after sexual intercourse may be indicative of cervical erosion or cancer.