Understanding the fontanelle in infants

1- What is a fontanelle?
The fontanelle is a soft area located between the bones of an infant’s skull. At birth, the baby’s skull is not fully formed: the skull bones are separated by sutures, leaving spaces called fontanelles. There are several fontanelles, with two main ones in a baby:

• Anterior fontanelle: Located at the front of the skull, at the top of the head, it is the largest and diamond-shaped. It is the fontanelle most parents are familiar with.

• Posterior fontanelle: Found at the back of the head, this fontanelle is much smaller and closes earlier than the anterior fontanelle.

2- The role of the fontanelle in infants
Fontanelles play several critical roles in a child’s development:

1. Facilitating birth: During delivery, the fontanelle allows greater flexibility of the skull, helping the baby’s head pass through the birth canal. The skull bones can overlap slightly during labor, making the passage easier.

2. Enabling brain growth: A baby’s brain develops rapidly during the first months and years of life. Fontanelles and sutures allow the skull to expand as the brain grows, ensuring sufficient space for this vital development.

3. Indicating health status: Pediatricians often use the fontanelle to monitor a baby’s overall health. For example, a sunken fontanelle can indicate dehydration, while a bulging fontanelle may suggest increased intracranial pressure, requiring medical attention.

3- The evolution of fontanelles
Fontanelles do not remain open indefinitely; they gradually close as the baby grows. The closure follows a normal, predictable timeline:

• Posterior fontanelle: This small fontanelle at the back of the head typically closes earlier, usually between 1 and 2 months of age.

• Anterior fontanelle: It takes longer to close, usually between 12 and 18 months. In some children, it may take up to 24 months, which is still within the normal range.

It is important to note that the closure of the fontanelles does not indicate the end of brain growth. Even after the fontanelles close, the skull sutures continue to allow moderate skull expansion to support brain development.

4- What to monitor regarding the fontanelle
It is normal for the fontanelle to be slightly sunken or bulging depending on the baby’s position or condition, such as when crying or lying down. However, some signs may require medical attention:

1. Sunken fontanelle: This can indicate dehydration. If you notice that the fontanelle is noticeably sunken, check to ensure your baby is getting enough fluids.

2. Bulging fontanelle: A persistently bulging fontanelle, especially if accompanied by fever or irritability, may signal increased pressure in the brain. It is advisable to consult a pediatrician immediately in such cases.

3. Premature closure: If the fontanelles close too early, it could restrict brain growth, a condition known as craniosynostosis. Regular medical check-ups help detect such issues promptly.

It is worth mentioning that the pulsing of the fontanelle is related to the passage of a blood vessel beneath it. Therefore, parents need not worry about whether the fontanelle pulses or not.

Conclusion
Fontanelles are more than just soft spots on your baby’s head; they play a vital role in your child’s growth and development. Understanding their function and evolution allows parents to better monitor their baby’s health. If you have any concerns about your child’s fontanelle, don’t hesitate to discuss them with your pediatrician during regular check-ups.

The Centre Pédiatrique de Bonapriso is here to answer all your questions and provide attentive medical care for your baby’s health.