Small tummy pain in early pregnancy may generally be caused by the following two reasons: First, because the pelvic cavity will be congested with blood during pregnancy, the uterus will gradually increase in size and the pregnant woman feels a slight swelling and pain in the abdomen. Secondly, due to the increasing size of the pregnant uterus, it will pull on the surrounding intrauterine ligaments, and the patient will also feel pain in the small of the abdomen during the pulling process. Then, due to the enlargement of the uterus, the skin on the surface of the abdomen is stretched, causing an uncomfortable sensation in the skin of the abdomen. In summary, the small stomach pain in early pregnancy is caused by a series of changes in the uterus and the ligaments surrounding the uterus brought about by pregnancy.