Girls with large stomachs and obesity, constipation, pregnancy, fibroids, ovarian cysts and so on. 1. Obesity: If girls have overeating, less exercise, etc., can be due to the accumulation of large amounts of fat in the abdomen and the phenomenon of a large stomach. 2. Constipation: the main symptoms of constipation are reduced frequency of defecation, dry feces, difficulty in defecation, abdominal distension and pain, loss of appetite, etc., and some of them may have a big belly due to the retention of feces in the intestinal tract. 3. Pregnancy: When some girls are pregnant, they may have a big stomach due to the growth and development of the fetus and the increasing size of the uterus. 4. Uterine fibroids: the cause of the disease is still unclear, and may be related to heredity, sex hormone level changes, etc. Most patients with fibroids do not have obvious symptoms. Most of the patients with uterine fibroids have no obvious symptoms, but a small number of patients have symptoms such as large stomach, lower abdominal distension and abnormal menstruation due to the enlargement of uterine fibroids. 5. Ovarian cysts: the disease may be related to the environment, diet, infection, etc. Some functional ovarian cysts may not have obvious symptoms, but some patients with the increase in the size of the ovarian cysts will appear abdominal distension, lower abdomen pressure, lumbar-sacral pain and other symptoms, which can also be manifested in the stomach becomes larger. There are many reasons for girls to have a big stomach, such as intestinal obstruction, intestinal cancer and so on. It is recommended to consult a doctor in time for examination, if it is clear that the disease is caused by, need to actively cooperate with the doctor’s treatment.