Brown discharge on the twelfth day of IVF transplantation may or may not be normal, such as transplantation failure, preeclampsia, gynecological diseases and other causes. 1. Embryo implantation: embryo implantation is an invasive process for the endometrium, embryo implantation may lead to a small number of endometrial capillary rupture, and then a small amount of bleeding, blood in the uterine cavity after a period of time of stagnation will be discharged will be manifested as a brownish secretion, secretion of the amount of relatively small, generally do not have to deal with special treatment. 2. Transplantation failure: due to poor embryo quality, poor endometrial tolerance and other reasons for transplantation failure, miscarriage, will be twelve days after the IVF transplantation of brown secretions. 3. Pre-eclampsia: IVF has been successful, IVF twelve days of low progesterone value in the body, not able to support the pregnancy will have a small amount of vaginal bleeding, may also show brown secretions, this situation is not normal. 4. Gynecological diseases: women with vaginitis, cervicitis and other gynecological diseases during in vitro fertilization, stimulated by inflammation, mucosal congestion, edema, transplantation after twelve days may have brown discharge. There are more reasons for brown secretions after twelve days of IVF transplantation, and the specific ones should be judged by examination in the hospital.