Hidden pain in the stomach on the eighth day after blastocyst transfer may be caused by mechanical injury of uterus, pain during implantation, inflammation or bleeding. 1. Mechanical injury of uterus: the hidden pain in the stomach on the eighth day after blastocyst implantation may be caused by the slight tugging and pulling injury to the uterus caused by the instruments used in the process of implantation, the symptom can be relieved on its own, and it is recommended to pay attention to rest and avoid strenuous exercise. 2.implantation pain: the patient in the eighth day the fertilized egg has begun to implant, development, is considered to be implantation pain, in the process of the uterine wall will produce a certain amount of stimulation, the body’s hormones will also change, so the patient’s tummy ache, belong to the normal physiological reaction, recommend that patients more bed rest, avoid exertion. 3. Inflammation or bleeding: If the patient has a vague pain in the stomach on the eighth day of embryo transfer, accompanied by a lot of vaginal bleeding and other phenomena, it may be related to the inflammation of the reproductive system or bleeding. Therefore, pregnant women with vague pain in the stomach after the transfer need to consult a doctor in time to clarify the specific causes and take appropriate methods of intervention.