The fetal head circumference can be known from the ultrasound examination during pregnancy, but this data can only be used as a reference, because the fetal position can also affect the ultrasound data, in general, the fetal double top of the neck value is 2 standard deviations larger than the actual gestational week, then the fetus may have malformations. If the ultrasound shows that the head of the fetus is only slightly larger than the normal standard value of the actual gestational week and there are no other abnormalities, this is not a pathology, but a result of the rapid development of the fetus, and mothers do not need to worry too much, they just need to control their diet properly. The ultrasound shows that the value of the top of the neck of the fetus is much larger than the standard value of the actual pregnancy week, exceeding 2 standard deviations, which means that the fetus has abnormal head growth, the body proportions of this kind of fetus are seriously uncoordinated, the trunk is very small, this kind of situation may be caused by hydrocephalus, or it may be congenital head malformation or tumor in the head, then the pregnant mother In this case, pregnant mothers need to do the appropriate pregnancy checkups and receive the appropriate medical advice. If the fetus’ head is not too big, it is normal and the mother does not need to worry about it or treat it. If it is much larger, you should undergo a detailed examination as soon as possible to find out if there is any malformation and to find out the cause in time.