What is the reason for a baby's small fontanelle?

The fontanelle is the gap in the baby's skull left when the skull bones are not tightly connected. The fontanelle is an important window that reflects the baby's development and physical health. Moreover, the characteristics of each baby's fontanelle are different. Some parents find that their baby's fontanelle is smaller than that of other children, and they are worried that there is something wrong with their child. So, what is the reason why babies have small fontanelles? Let’s take a closer look at it below.

What to do if your baby's fontanelle is small

If the baby's fontanelle is too small, it is necessary to measure the head circumference regularly, that is, to observe whether the head circumference is within the normal range before the baby is one month old. The growth rate of the head circumference should be checked every month or every two months and compared with that of normal babies to see if there is any obvious lag. If the baby's head circumference develops normally and continues to do so after 3-4 months of follow-up, even if the fontanelle is a little smaller, it will not affect the development of the brain.

However, if the head circumference growth value is also abnormal, such as the head circumference is 2 standard deviations smaller than that of babies of the same age and gender, and the baby's ability to lift his head, sit, walk, and speak cannot keep up with babies of the same age, it means that his brain development may be delayed. At this time, you should go to the hospital to conduct developmental assessment and intelligence testing of your baby. If necessary, special examinations such as CT and MRI of the brain can be performed.

For newborn babies, the skull ossification is not complete, so the skull bones are not well connected to each other. Some places are connected by connective tissue membranes, which are called fontanelles.

The fontanelles of children are divided into anterior and posterior. The anterior fontanelle is a diamond-shaped gap formed by the two frontal bones and the parietal bones. It is 1.5×2 cm in size at birth and increases with the increase of head circumference. It gradually ossifies after 6 months and is completely closed before 18 months. The posterior fontanelle is a small triangular gap formed by the two parietal bones and the occipital bone. Some are closed or very small at birth and are completely closed within 3 months. The fontanelle we usually refer to is the anterior fontanelle.

If the fontanelle closes prematurely and the head circumference is significantly smaller than normal, it may be due to brain maldevelopment. Some normal children have a fontanelle that is only the size of a fingertip when they are 5 to 6 months old. It seems to be closed, but in fact it has not ossified, so it cannot be considered that the fontanelle is closed prematurely.

When your baby is sick, touching the fontanelle can have predictive significance. If the fontanelle is full or obviously protruding, it indicates hydrocephalus, encephalitis, meningitis, subdural edema, tetracycline and vitamin A poisoning, etc.; if the fontanelle is obviously sunken, it is common in severe dehydration caused by diarrhea in children. At this time, you should seek medical treatment in time.