The blastocysts that do not implant in the uterus are expelled with menstruation. Blastocyst without implantation refers to biochemical pregnancy in clinical practice, which mainly refers to the fact that the fertilized egg stops developing without successfully implanting in the uterus; the sperm combines with the egg to form a fertilized egg, which usually enters into the uterus through the swing of the fallopian tubes 7-10 days after fertilization, and normally implant and develops in the uterus to form a gestational sac, which gradually develops to form a fetus. Blastocyst does not implant mainly due to abnormal quality of fertilized egg, poor development of uterine lining, abnormal secretion of hormone level and other reasons that can not continue to develop into a gestational sac; Blastocyst does not successfully implant, under the influence of hormone level, the uterine lining is shed to form menstruation, and the blastocysts will be discharged out of the body along with the shedding of the uterine lining and menstrual blood. If the recurrent failure of the blastocyst to implant seriously affects the normal pregnancy, it is necessary to go to the hospital in time to find out the cause of the problem and treat the cause of the problem.