The normal value of the biparietal diameter at 24 weeks of pregnancy is around 5.75-6.6 cm. The biparietal diameter is the length of the widest part of the fetus between the left and right sides of the head, also known as the largest transverse diameter of the head. It can be used to estimate the size of the fetus, to check the development of the fetus, to determine the head circumference of the fetus, and to assess whether the fetus is suitable for normal delivery. The size of the biparietal diameter varies from person to person and is related to nutrition during pregnancy, fetal growth retardation and genetics. If the biparietal diameter is too small, you should be cautious of microcephaly; if the biparietal diameter is too large, you should be cautious of hydrocephalus. Therefore, it is important to have regular maternity checkups during pregnancy and ensure balanced nutrition. In the 24th week of pregnancy, you should check for gestational diabetes and take enough iron-containing foods to prevent iron-deficiency anemia, including black sesame, black beans, peanut rice, animal offal and dates. If you are diagnosed with anemia by pregnancy test, it is recommended to take iron supplements in time.