The standard comparison table of fetal biparietal diameter refers to the standard values of fetal biparietal diameter at different weeks of gestation. The fetal biparietal diameter is the largest transverse diameter of the fetal head in the left and right directions, also known as the large transverse diameter of the fetal head. Generally after 12 weeks of gestation, the fetal skull forms a distinct halo, so the biparietal diameter measurement is performed from 12 weeks onwards. The fetal biparietal diameter is usually around 2.0cm at 13 weeks, and grows about 3mm per week until 31 weeks, and 1.5mm per week between 31 and 36 weeks. The biparietal diameter of a full-term fetus is usually between 9.0-10.0cm. If the biparietal diameter of a full-term fetus is more than 10.0 cm, the possibility of a giant baby should be considered. On the contrary, if the fetal biparietal diameter is less than 9.0cm, intrauterine growth retardation should be excluded.