Stomach pain at 31 weeks of pregnancy may be caused by false contractions, preterm labor, gastroenteritis and so on, which can be dealt with by proper rest and suppression of contractions. 1. False contractions: when a pregnant woman is 31 weeks, the head of the fetus begins to appear to descend, she will feel a vague pain in the stomach, but this contraction is not regular, and can be relieved soon, this situation can not worry too much, you can rest properly. 2. Preterm labor: if the pregnant woman feels her stomach in a burst of tightness, swelling, and pain with regularity, it is necessary for the pregnant woman to go to the hospital for examination, to determine the cause of the pain through the medical examination, if due to the dilatation of the cervix caused by contractions, the need for pregnant women to timely inhibit contraction therapy, such as intravenous drip magnesium sulfate. 3. gastroenteritis: 31 weeks pregnant stomach pain, may also be eating unclean food caused by gastroenteritis, if accompanied by vomiting, diarrhea and other symptoms, it is recommended to gastroenterology. Pregnant women 31 weeks pregnant should avoid sex, do not exercise strenuously, avoid heavy physical labor. It is recommended to go to the hospital in time, clear diagnosis and treatment according to medical advice.