Vaginal bleeding, spotting, or an increased amount of vaginal discharge--especially heavy bleeding and any prior to week 37--can be serious. Vaginal bleeding during pregnancy can range from slight and painless to heavy with abdominal or pelvic pain, and it can indicate a number of serious conditions like an ectopic pregnancy or miscarriage. If you’re experiencing bleeding, it’s best to call your doctor right away, even if the symptom turns out to be totally harmless.