Belly pain, also known as abdominal pain, occurs in the first month of pregnancy and may be caused by physiological factors, such as fluctuations in body hormones, stimulation of the development of the gestational sac, excessive secretion of stomach acid, etc. It may also be caused by gynecological inflammation, ectopic pregnancy, pre-eclampsia and other pathological factors. I. Physiological factors: After intrauterine pregnancy is confirmed in early pregnancy, abdominal pain may occur in pregnant women because of the fluctuation of hormones in the body and the stimulation of the development of the gestational sac, which can generally be gradually relieved. In addition, in early pregnancy, some pregnant women may experience excessive secretion of stomach acid, which may lead to pain in the upper abdomen. Pathological factors: 1. gynecological inflammation: if the pregnant woman has pelvic inflammatory disease, cervicitis, vaginitis and other diseases, it will induce abdominal pain; 2. ectopic pregnancy: it is often called ectopic pregnancy, if the pregnancy is clearly detected by blood test for HCG or urine test and abdominal pain suddenly appears, especially unilateral lower abdominal pain, it is necessary to be highly alert to the possibility of ectopic pregnancy, and timely consultation and examination is needed; 3. pre-eclampsia Miscarriage: if intrauterine pregnancy is confirmed by ultrasound and there is abdominal pain that persistently cannot be relieved, gradually worsens or is accompanied by vaginal bleeding, you need to be alert to the possibility of pre-eclampsia miscarriage and go to the obstetrics department of the local hospital in time; 4. Other diseases: such as acute gastroenteritis, appendicitis, ureteral stones, etc., abdominal pain can occur. Overall, abdominal pain in early pregnancy should still be taken seriously, and it is recommended to go to the hospital in a timely manner to clarify the cause and then provide targeted treatment.