Bleeding sixteen days after the transfer may refer to bleeding sixteen days after having an IVF embryo transfer. It may be a normal phenomenon, pre-miscarriage, onset of menstruation, or may be considered to be related to inflammation in the gynecological area. 1. Normal phenomenon: a small amount of vaginal bleeding 16 days after the transfer, if it does not last long, it is considered normal and can be closely observed. 2. Pre-eclampsia: The amount of vaginal bleeding gradually increases, accompanied by abdominal pain, it is recommended to go to the obstetrics department of the hospital in time to find out whether it is related to pre-eclampsia in the early stage of pregnancy. 3. Menstrual flow: abdominal pain after transplantation accompanied by menstrual bleeding may also be caused by the failure of transplantation, while vaginal bleeding may be normal menstrual flow. 4. Gynecological diseases: If there are gynecological diseases, such as cervicitis, vaginitis may cause bloody discharge, resulting in vaginal bleeding. Vaginal bleeding sixteen days after transplantation is recommended to be closely observed, and if necessary, go to the gynecology and obstetrics department of the hospital for examination and clear diagnosis.