The vague pain in the stomach in the third month of pregnancy can be seen as a physiological phenomenon after pregnancy, pre-eclampsia or ectopic pregnancy, and the abdominal pain caused by different reasons is handled differently. 1, normal physiological phenomenon or pre-eclampsia: If the intrauterine pregnancy is clear, the vague pain in the stomach at this time is mainly considered to be a physical abdominal pain caused by pregnancy, which is a normal physiological phenomenon; or it is considered to be caused by the enlargement of the uterus, which pulls the surrounding ligaments. This kind of pain is often short-lived, aggravated by exertion, and can be relieved after lying down and resting. If the vague pain in the lower abdomen is prolonged and gradually worsens, or if it is accompanied by a little vaginal bleeding, the possibility of pre-eclampsia or miscarriage cannot be ruled out, and immediate hospital consultation is required. 2.Ectopic pregnancy: If there is no clear intrauterine pregnancy, the presence of vague pain in the lower abdomen in the third month of pregnancy needs to be alert to the possibility of ectopic pregnancy. Ectopic pregnancy is often manifested as prolonged, persistent pain in one side of the lower abdomen, and the pain is gradually stronger, at which time immediate medical attention is required, because the ectopic pregnancy progresses rapidly and can cause syncope, hemorrhagic shock and even life-threatening when rupture occurs. 3, other causes: the hidden pain in the lower abdomen in the third month of pregnancy does not exclude gastroenteritis, pelvic inflammatory disease, appendicitis and other causes, and it is also necessary to seek medical attention in a timely manner to clarify the cause. To sum up, when you encounter vague pain in your stomach in the early stages of pregnancy, you should consult a hospital to clarify the cause based on safety considerations, do not carry it at home to avoid ectopic pregnancy rupture hemorrhage and life-threatening.