A natural miscarriage generally stops bleeding within a week; if the bleeding continues beyond a week, it is considered abnormal. This is because in most cases of natural miscarriage, the embryo and the decidua are expelled together, followed by uterine contractions, resulting in some vaginal bleeding. Normally, such bleeding should not persist beyond a week. If vaginal bleeding continues past this period, an ultrasound should be conducted to examine whether the uterine cavity is clean and free of any residual embryonic tissue. If remnants are found, it may be necessary to take some medications to promote blood circulation and remove the residual tissues.