Transplantation here refers to IVF transplantation, and the vague pain in the stomach on the third day of transplantation may be caused by pelvic congestion or uterine contraction, fluid irritation of the peritoneum, gastrointestinal disorders and other reasons. 1. Pelvic congestion or uterine contraction: IVF is an invasive behavior, to invasively break through the endometrium, and firmly embedded in the endometrium, there may be a certain impact on the endometrium, resulting in pelvic congestion or uterine contraction, the third day of transplantation will have a vague pain in the abdomen. 2. Liquid stimulation of the peritoneum: is a fresh cycle of transplantation of women, ovary enlargement after egg retrieval obvious or retrieve eggs after a small amount of liquid, blood, etc., stimulation of the peritoneum will also have a vague pain in the feeling. 3. Gastrointestinal disorders: the vague pain in the stomach on the third day of transplantation may have nothing to do with transplantation, but is the discomfort caused by gastrointestinal disorders, such as indigestion, intestinal flora disorders, constipation and other causes. Therefore, there are many reasons for the vague pain in the stomach on the third day of transplantation, and it is recommended to go to the hospital in time in order to clarify the specific causes of the disease and give targeted treatment.