The vague pain in the stomach at 4 weeks of pregnancy can be seen as a result of physical pain caused by pregnancy, but also due to other abnormal conditions. 1.Physiological phenomenon: If early intrauterine pregnancy is clear, the lower abdominal pain at this time is mainly considered to be physical abdominal pain caused by pregnancy, which is a normal physiological phenomenon, often manifested as a short period of time, pain in the lower abdomen, aggravated by exertion, and can be relieved after lying down and resting. 2.Premature miscarriage or miscarriage: If early intrauterine pregnancy is clear and the pain is long and gradually aggravated, or accompanied by a little vaginal bleeding, the possibility of premature miscarriage or miscarriage cannot be ruled out, and it is necessary to immediately go to the hospital to recheck blood HCG and early pregnancy ultrasound to clarify the diagnosis. 3, ectopic pregnancy: If there is no clear intrauterine pregnancy, the vague pain in the lower abdomen at the early stage of pregnancy needs to be alerted to the possibility of ectopic pregnancy, which is often manifested as prolonged and persistent pain in one side of the lower abdomen, at which time immediate medical attention is needed, because ectopic pregnancy progresses rapidly and can cause syncope, hemorrhagic shock and even life-threatening when rupture occurs. 4, other diseases: if the pregnant woman has not been to the hospital, she can test positive for urine test paper at home by herself, which does not exclude the possibility of false positive, and the hidden pain in the lower abdomen does not exclude gastroenteritis, pelvic inflammatory disease, appendicitis and other causes. In summary, lower abdominal pain in the fourth week of pregnancy can be seen as a normal physiological phenomenon, but also due to pre-eclampsia, ectopic pregnancy or other diseases. If you experience lower abdominal pain in early pregnancy, you should go to the hospital in time to clarify the cause, do not wait at home to avoid ectopic pregnancy rupture hemorrhage, hemorrhagic shock, or even life-threatening.