In the third trimester, the uterus has risen from the pelvic cavity to the abdominal cavity. If bulging occurs, the most common reason is that the uterus is relatively sensitive, and the uterine contractions will manifest as a bulging stomach, as long as you pay attention to a little rest. However, if frequent bulging is not normal, it may be caused by pre-eclampsia, it is recommended to go to the hospital for further examination, combined with ultrasound and laboratory tests to give the appropriate treatment. In addition, if the stomach bulges in the third trimester, it is also necessary to exclude the possibility of tumors in the pelvis, for example, through ultrasound examination to find out whether there is a tumor phenomenon. The bulge will disappear after defecation.