A baby born with a small biparietal diameter may also be normal. The biparietal diameter of the fetus will be measured when the pregnant woman undergoes an ultrasound during her labor and delivery visit. Each measurement will be compared to the normal gestational week and also to the results of the previous test. If the biparietal diameter is small compared to the normal gestational week, but is still growing when compared to the previous measurement, and there are no other problems with the fetus, the fetus may have been born with a small head and will develop normally after birth. If the biparietal diameter of the fetus is small and combined with other malformations, it is considered that there are problems with the baby after birth, and you need to choose whether or not to end the pregnancy under the guidance of your doctor, depending on the malformations. Biparietal diameter is only one of the references. Whether the development of the fetus is normal or not also needs to be considered in combination with a series of indicators such as abdominal circumference, femur diameter, facial development and so on. Regular checkups are recommended, and if there are any special circumstances, consult a specialist in time.