The normal anterior halogen closes at about 1-1.5 years of age after birth, and if it closes too early or too late, you should seek medical attention to find out why. The posterior halogen is usually closed at birth or within 2-3 months. Late closure and enlargement “Late closure” refers to children who have not yet closed by the age of 1.5 years, but have been seen to be delayed until the age of 3 years; “Enlargement” refers to those whose midpoint of the opposite side of the rhombus is more than 2 cm in line with the above criteria. So, how to distinguish delayed fontanelle closure from other fontanelle growth abnormalities? The following are the diagnostic methods for delayed closure of fontanelle: 1. The most common cause of sunken fontanelle is the lack of water in the baby’s body, such as diarrhea, which leads to the sunken fontanelle. In this case, the baby needs to be replenished with fluids immediately. In order to lower the intracranial pressure, high doses of dehydrating agents are used, thus causing the fontanelle to sink due to dehydration. The baby’s body should be hydrated promptly to prevent metabolic disorders in the body caused by excessive dehydration. Malnourished, thin babies, their fontanels often show the phenomenon of depression. 2, premature closure of fontanelle When the baby’s fontanelle is prematurely closed, the size of its head circumference must be measured. If the size of the head circumference is lower than the normal value, it may be a brain dysplasia. Some babies with normal body, at the age of 5-6 months, the fontanelle is only fingertip size and seems to be closing, but in fact it is not ossified, so you should ask your doctor to identify it. 3.Delayed fontanel closure Delayed fontanel closure mainly refers to the baby has passed 18 months, but the fontanel has not yet closed, mostly seen in rickets, cretinism. Delayed fontanel closure, a few are caused by hydrocephalus or other causes of increased intracranial pressure, should go to the hospital for further examination. 4, fontanelle too large fontanelle too large, generally refers to the baby soon after birth, the front fontanelle reached 4-5 cm size. If the fontanelle is too large, the first possibility is that the baby has congenital hydrocephalus, and the second possibility is that it is caused by congenital rickets. In babies with congenital hydrocephalus, the fontanelle is not large at birth because the baby’s head is squeezed during the birth canal. However, a few days after birth, the fontanelle is usually gradually larger. In babies born with congenital rickets, not only is the fontanelle large, but also the posterior fontanelle is large, and a bone suture (sagittal suture) in the middle is wider, connecting the front and back of the fontanelle.