Whether or not it is useful to use birth control injections for bleeding in the third trimester of pregnancy needs to be determined by the cause of the bleeding and the amount of bleeding. If the bleeding is small and the bleeding is due to exertion, low position of the placenta, etc., the birth control injection may be useful. If the bleeding is heavy and the bleeding is due to an abnormality in the embryo itself, the birth control injection may not be effective. Bleeding in the third trimester may be caused by poor rest, emotional instability, external trauma, low placenta position, embryo abnormality, and so on. If there is a pre-eclampsia due to a problem with the embryo itself, there is a high probability that the birth control will fail and the miscarriage will inevitably end up being a miscarriage. Fertilization may also be ineffective if the external stimulus is too great, resulting in excessive fetal damage and heavy bleeding. If the external stimulus causes less damage to the fetus and less bleeding, and the bleeding gradually decreases during the process of birth control, then the birth control injection is useful. When vaginal bleeding occurs after pregnancy, you need to consult a doctor for timely examination to clarify the cause of the disease and standardize the treatment under the guidance of the doctor.