AC is the abbreviation for fetal abdominal circumference during ultrasound examinations during pregnancy, which is the data obtained by measuring the fetus’ belly for one week. The abdominal circumference value, combined with the fetal head circumference, biparietal diameter and femur length, is used to determine whether the baby’s physical development is normal, and is also one of the indicators for projecting the size of the fetus. If some pregnant mothers have irregular menstrual cycles, the above mentioned values measured by ultrasound of the fetus in early pregnancy can be used to estimate and check the expected date of delivery. Therefore, pregnant mothers should have regular maternity checkups and have ultrasound examinations at the right time according to the doctor’s advice to detect abnormalities and intervene in time. During pregnancy, pregnant mothers should have a balanced diet, with meat and vegetables, diversified diet, eat more fresh vegetables and appropriate amount of fruits, keep a happy mood, and control the weight of the fetus to avoid huge babies in order to increase the chances of normal delivery.