The standard fetal abdominal circumference at 26 weeks of gestation is about 21.62±2.3cm, which is within the normal range. The fetal abdominal circumference varies at different weeks of gestation, generally at 10.32±1.92cm at 16 weeks, 29.44±2.83cm at 36 weeks and 31.49±2.79cm at 40 weeks. The fetal abdominal circumference is the maximum length of the horizontal circumference around the fetal abdomen. It can be used to evaluate the development of the fetus, determine whether the fetus is developing normally, and also assist in making decisions about the mode of delivery. 1.Large abdominal circumference: If the fetal abdominal circumference is large, it means that the fetus is fat, and it is necessary to consider the possibility of difficult delivery, and if necessary, a cesarean section can be chosen; 2.Small abdominal circumference: If the fetal abdominal circumference is small, it means that the fetus may be thin and small, and the pregnant woman should pay attention to proper nutrition to promote fetal development. The woman should be aware that the test results show that the fetal abdominal circumference is large or small, but also combined with other indicators of the fetus comprehensive analysis and judgment, and can not be based on abdominal circumference alone to confirm the fetal development is normal or abnormal. In addition, the 26th week of pregnancy is in the middle of pregnancy, the fetus is growing faster at this time, pregnant women should increase nutrition, eat less and more meals to avoid indigestion and constipation and other problems.