The pain below the belly button at 28 weeks of pregnancy may be due to physiological abdominal pain, placental abruption, gastrointestinal diseases and other reasons. 1. physiological abdominal pain: 28 weeks pregnant below the navel pain may be a normal phenomenon, with the growth of the fetus uterus gradually increased, resulting in the outside of the uterus tissues and organs are squeezed, resulting in pain below the navel, this is the physiological abdominal pain that occurs in pregnancy, do not need special treatment. 2. placental abruption: 28 weeks pregnant below the navel pain may be placental abruption, this time the pain is intense, persistent, unrelieved, hardening of the abdomen, may also be accompanied by vaginal bleeding and other discomforts. 3. Disease: Pregnancy 28 weeks below the navel pain may also be caused by gastrointestinal diseases, such as appendicitis, acute cholecystitis, acute pancreatitis, etc., will appear related symptoms. If the pain below the navel at 28 weeks pregnant persists and becomes more and more intense, you should go to the regular hospital in time.