Both normal fetuses and malformed fetuses have hydrocephalus, but the amount of hydrocephalus is different. If the amount of hydrocephalus is high, it will cause the widening of the ventricles and lead to significant abnormalities during ultrasound. For a normal fetus, there will be hydrocephalus, but because the amount of hydrocephalus is not large, it will not lead to a significant widening of the ventricles and therefore no abnormalities will be detected during the ultrasound. However, it does not mean that there is no fluid in the fetus’ head, because there is fluid in every human head. For malformed babies, the amount of cerebrospinal fluid is often very high and the fluid is not circulating well, so it will indirectly cause the widening of the ventricles, such as the widening of the lateral ventricles by more than one centimeter, so during the 4D ultrasound, if the widening of the ventricles is more than one centimeter, it is often considered more likely to be a malformed baby, and hydrocephalus is the most common. If it is indeed hydrocephalus that is the cause of the malformation, then we can only consider inducing labor to terminate the pregnancy. Since there is no other way to treat the malformation, doctors will recommend induction of labor to terminate the pregnancy.