Bloating in the 21st week of pregnancy may be a normal phenomenon, but we can’t rule out pathological causes such as indigestion, constipation and other reasons. 1. Normal phenomenon: 21 weeks of pregnancy due to the pregnant woman’s uterus enlargement, may be pressed to the gastrointestinal tract, resulting in a feeling of bloating, usually after adjusting the diet and appropriate exercise, the symptoms can be improved. 2. Indigestion: 21 weeks pregnant women may suffer from indigestion, may be due to excessive secretion of gastric acid, Helicobacter pylori infection, dietary irregularities, maternal anxiety, etc., often manifested as a bloated stomach, accompanied by loss of appetite, belching and other symptoms. 3. Constipation: 21 weeks pregnant belongs to the mid-pregnancy, most pregnant women during this period may be constipated, resulting in the occurrence of bloating, mainly due to the slowing down of intestinal peristalsis, dietary fiber intake is insufficient and so on. If a pregnant woman has a bloated stomach in the 21st week of pregnancy, accompanied by the above symptoms, it is recommended to consult a doctor in a timely manner, under the guidance of the doctor, improve the relevant examination, clarify the cause of the disease, and symptomatic treatment.