How long does it take for a child's anterior fontanelle to close?

When a baby is just born, there are two places on the top of the head without bone, which are called fontanelles. As the child grows and develops, the fontanelles will gradually close when the child is about three months old. However, for some children, they may not close properly. Parents must pay attention at this time. There are many reasons for poor closure of the fontanelle, the most common ones are hydrocephalus, rickets, and even cretinism, etc., which are quite harmful to the child.

How long does it take for a child's anterior fontanelle to close?

When a baby is born, there are two boneless "windows" on the front and back of the head, which are called fontanelles. The posterior fontanelle will close 3 months after the baby is born, while the anterior fontanelle will not close until the baby is 1 and a half years old. The fontanelle that people often mention refers to the anterior fontanelle. Whether the fontanelle closes on time indicates whether the baby's development is normal. Late closure of the fontanelle is often seen in infants with rickets, hydrocephalus, cretinism and rapid growth.

The development standard of the baby's fontanelle is that the anterior fontanelle located on the top of the baby's head is diamond-shaped and is about the size of an adult's thumb at birth (1.5-2 cm, the distance between the midpoints of the opposite sides). Since the brain grows slightly faster than the skull in the first few months after birth, the anterior fontanelle of a normal baby may slightly increase with the increase of head circumference during this stage, but it is generally not larger than 3.0 cm and not less than 1.0 cm, and it does not protrude outward. The baby also does not show symptoms such as excessive sweating, night terrors, and irritability.

If the baby's anterior fontanelle is larger than 3 cm, or is accompanied by other abnormal symptoms such as sweating, night terrors, irritability, etc., you should consider whether the baby has rickets or other cranial diseases, and ask a doctor to check it out in time.

The anterior fontanelle usually starts to gradually shrink again around 6 months after birth, and generally closes at 12 to 18 months.

The posterior fontanelle is located in the middle of the back of the baby's head and is triangular in shape. When the baby is born, the posterior fontanelle is very soft and has not yet closed. It usually starts to close 2-3 months after the baby is born. The baby's posterior fontanelle lacks the protection of the skull, so parents should pay attention to prevent it from being hit by hard objects before the baby's posterior fontanelle closes, but it can be gently washed with water. The closure of the baby's posterior fontanelle indicates that the baby's head development is becoming complete and it is also the arrival of the second peak period of the baby's brain cell development.