Pregnant women need to analyze the fetal head size according to more specific circumstances, it may be a normal phenomenon, or disease state, such as hydrocephalus, overnutrition and so on. 1. Normal phenomenon: in the process of pregnancy, the specifics of fetal development is a personal difference, if in the standard line within one to two weeks of the threshold, are relatively normal phenomenon; in addition, if both parents have a large head, then due to heredity, the fetus may appear to be slightly larger than the average fetus head. 2. Hydrocephalus: when the fetus has hydrocephalus, the ventricles of the brain may be widened and malformed, and the examination will show that the fetus has a big head; 3. Over-nutrition: when the fetus is over-nourished due to excessive maternal intake, it may also have a large head, and it is recommended to control the diet reasonably at this time. Pregnant women are recommended to have regular medical checkups, and if there is a persistent enlargement of the fetal head, they need to be vigilant and communicate with their doctors in time to find out the causes.