At 39 weeks of pregnancy, the abdominal circumference of the fetus is about 31-37 cm. As long as the test results are within this range, the fetus is relatively normal. If the fetal abdominal circumference is large, beyond the normal range, it may be caused by fetal intestinal distension, pregnant women in late pregnancy over-eating, the mother’s improper diet can lead to fetal intestinal distension, no other comorbidities, fetal distension can be self-absorption; excess nutrition can accelerate the growth rate of the fetus, thus increasing the fetal abdominal circumference, if the formation of huge children, pregnant women are recommended to cesarean delivery. If the abdominal circumference of the fetus is small, it may be due to the fetus less nutritional absorption, at this time the fetus is generally thin and small overall. Before delivery, pregnant women can take appropriate nutritional supplements, such as consuming calcium and high-quality protein, including milk, soy products, seafood, bone broth, etc. It is also recommended to strengthen nutrition after the birth of the fetus. If the fetus has abnormal abdominal circumference, combined with other systemic abnormalities or developmental abnormalities, it may suggest the presence of chromosomal abnormalities. It is necessary to measure the fetal biparietal diameter, head circumference and femur length comprehensively to determine the fetal weight, and if conditions allow, early cesarean section can be performed to treat the newborn.