What are some causes of bleeding during pregnancy?

There are a variety of reasons that someone might start bleeding during pregnancy, such as implantation of the eggs in the uterus, miscarriage, an ectopic pregnancy, cervical changes, infection, placenta previa, placenta abruption, uterine rupture, vasa previa, or premature labor. There are also possibilities that the bleeding may be due to an injury to the cervix, polyps or even cancer.