Fetal abdominal circumference of 345mm is on the fat side, may be due to maternal over-nutrition, pregnant women suffering from diabetes and other conditions caused by the specifics of the proposal to go to the hospital in a timely manner to find out the causes of the disease, and then according to the causes of targeted treatment. 1. Pregnant women overnutrition: mainly because of pregnant women during pregnancy weight gain too fast resulting in excess nutrition of the fetus is likely to lead to fetal abdominal circumference of the situation. It is recommended that pregnant women should have a balanced nutrition during pregnancy, avoid eating too much fat, sugar and other foods, but also can eat more fruits and vegetables. You can also eat more fruits and vegetables. You can also do more exercise to keep your body healthy. 2. Maternal diabetes: It is mainly due to the fact that the fetus absorbs too much nutrients and develops faster, resulting in an increase in abdominal circumference, as well as an increase in the length of the femur and the circumference of the head, resulting in the phenomenon of a large child. It is recommended to go to the hospital to consult a professional doctor for treatment. Fetal abdominal circumference of 345mm belongs to some fat, it is recommended that pregnant women during pregnancy must strictly control their own diet, and actively go to the hospital for examination, usually also need to appropriate supplementary nutrition and exercise, reduce the intake of high calorie, high fat, high sugar food.