If the fontanelle closes earlier than 1 year of age, it is considered to be closed too early. However, there is a great deal of individual variability in fontanelle closure, which is influenced by genetics, nutrition and disease. If the fontanelle closes earlier than 1 year of age and the head circumference is small, and there is also cognitive and psychological developmental delay, such as not being able to stand alone at 1 year of age and not being able to sit alone at 9 months of age, then microcephaly is present, and the child needs to go to the hospital for a cranial magnetic examination and necessary early rehabilitation training. If the head circumference is within the normal range except for the early closure of fontanelle, and all the developmental indicators of the baby are normal, there is no need to worry, only regular medical checkups at the child health department.