Small stomach pain in pregnant women may be caused by physiological reasons, pre-miscarriage, ectopic pregnancy, preterm labor, placental abruption, acute gastroenteritis and other reasons. 1. Physiological reasons: the gradual increase of the uterus during pregnancy, the pelvic floor ligaments have a pulling effect, causing pain in the lower abdomen, which is gradually relieved after appropriate bed rest. 2. Pre-eclampsia: Pre-eclampsia is characterized by paroxysmal lower abdominal pain, accompanied by a small amount of vaginal bleeding. This condition can be clearly diagnosed by checking the blood HCG (human chorionic gonadotropin) level and progesterone. 3. Ectopic pregnancy: Ectopic pregnancy can also cause pain in one side of the lower abdomen, accompanied by irregular vaginal bleeding, and the pain will worsen when the pregnancy ruptures. Ectopic pregnancy can be diagnosed by ultrasonography, blood HCG test, and examination of the posterior vaginal fornix. 4. Preterm labor: Preterm labor may also be characterized by irregular lower abdominal pain, with or without cervical canal shortening, which can be diagnosed with the help of history and ultrasonography. 5. Placental abruption: Placental abruption can also be manifested as lower abdominal pain, which is continuous, non-intermittent hypotonic abdominal pain, and in severe cases, it can appear as a plate-like abdomen, and it can be accompanied by vaginal bleeding, which can be diagnosed by combining with clinical manifestations and ultrasonography. 6. Acute gastroenteritis: unclean diet or improper diet can cause vomiting, diarrhea, lower abdominal pain and other symptoms, combined with the history, stool examination can help diagnosis. There are many causes of pain in the lower abdomen of pregnant women, it is necessary to go to the hospital in a timely manner, and identify the causes, symptomatic treatment.