There are many possible reasons for this. 1. it may be early pregnancy reaction, usually accompanied by vomiting, mainly due to increased secretion of stomach acid in early pregnancy, and may affect the ligaments supporting the uterus, which is a normal phenomenon; 2. it may be pressure pain due to the enlargement of the uterus, mostly occurring in the first four months of pregnancy, mainly due to the growth of the uterus leading to other parts of the abdomen being squeezed; 3. The pain is mainly caused by the squeezing of other parts of the abdomen due to the growth of the uterus; 3. It may be early contractions, which usually have a tight feeling without vaginal bleeding; 4. It may be pain in the round ligament of the uterus, which is caused by the growth of the ligament supporting the uterus; 5. It may also be dry stools, but the increase in the size of the uterus will increase friction and painful bouts, which can be relieved by eating more foods that promote bowel movements.