If the pain is located around the belly button and is paroxysmal, accompanied by nausea and vomiting, it is usually due to improper diet or gastrointestinal tract inflammation caused by gastrointestinal tract cramping. If the pain is located in the lower abdomen, with continuous vague pain, accompanied by abnormal vaginal discharge, it is considered to be abdominal pain caused by pelvic inflammatory disease during pregnancy. 3. If the abdominal pain is located in the lower abdomen, with a falling sensation, paroxysmal and gradually increasing, it is considered to be caused by uterine contractions, which may lead to preterm miscarriage or premature birth.