Stomach pain in the fifth month of pregnancy can be caused by the following reasons:1. The possibility of preterm labor, preterm labor will be abdominal pain accompanied by vaginal bleeding.2. Gastrointestinal disorders, such as acute gastroenteritis, mainly due to the eating of unclean food.3. Inflammatory bowel disease may cause stomach pain, such as ulcerative colitis, Crohn’s disease, etc.4. Gynecological inflammatory diseases, such as annexitis.5. Urinary system diseases, such as ureterolithiasis, kidney stones, etc. The pain may be caused by some inflammatory bowel diseases, such as ulcerative colitis, Crohn’s disease, etc. 4. If you have stomach pain in the fifth month of pregnancy, it is recommended that you go to a regular hospital to complete the relevant examinations and give timely and effective symptomatic treatment after a clear diagnosis.