Infant’s fontanel is divided into anterior fontanel and posterior fontanel, the anterior fontanel closes later, at the latest at the age of 2 years, and the posterior fontanel closes earlier, at the latest at about 6~8 weeks after birth. 1. The anterior fontanel is a diamond-shaped cross-bone gap junction in the center of the front part of the head of infants and young children, it is the largest bone gap junction on the skull, generally about two to four centimeters long and wide in newborn babies, in infants and young children around 6 months of age and gradually ossify and become smaller, the latest in 2 years of age closure. 2. posterior fontanel near the head and occiput, is the two sides of the parietal bone and occipital bone between the bone gap formed by the triangular gap, under normal circumstances, the baby was born after the fontanel is very small or already closed, the latest in the birth of 6 to 8 weeks closed. Early closure of the fontanel can be seen in children with congenital craniosynostosis and microcephaly, and delayed closure of the fontanel can be seen in children with vitamin D and calcium deficiencies. Normally, a baby’s fontanel is flat and soft. When a baby suffers from a disease such as meningitis that causes an increase in intracranial pressure, the fontanel will bulge; when a baby is dehydrated, the fontanel may be sunken. If your baby’s fontanel shows any of these symptoms, please consult a doctor promptly to find out the cause so as not to delay the condition.