when do fontanelles close

3 min read 13-03-2025

The soft spots on a baby's head, known as fontanelles, are a source of fascination and sometimes worry for new parents. Understanding when these fontanelles close is crucial for reassuring yourself and recognizing potential issues. This article will provide a comprehensive guide to fontanelle closure, addressing common concerns and offering advice.

What are Fontanelles?

Fontanelles are membrane-covered spaces between the bones of a baby's skull. They allow the skull to be flexible during birth, navigating the birth canal more easily. These spaces also accommodate the rapid brain growth during a baby's first year. There are two main fontanelles:

Anterior Fontanelle: This is the larger, diamond-shaped fontanelle located at the top of the baby's head.
Posterior Fontanelle: This smaller, triangular fontanelle is situated at the back of the baby's head.

When Does the Anterior Fontanelle Close?

The anterior fontanelle is the one parents most often ask about. Its closure is a gradual process. Generally, the anterior fontanelle closes between 9 and 18 months of age. Most babies will have it closed by 12-18 months. Some babies may have it close earlier or later within this range, and that's often perfectly normal.

What if the Anterior Fontanelle Closes Early?

Early closure of the anterior fontanelle (before 9 months) can sometimes indicate underlying issues such as craniosynostosis (premature fusion of the skull bones). Craniosynostosis can affect brain development and require medical intervention. If you're concerned about early closure, consult your pediatrician immediately. They can perform a physical exam and order imaging tests if necessary.

What if the Anterior Fontanelle is Still Open After 18 Months?

While most anterior fontanelles close by 18 months, some may remain open a little longer. This isn't always a cause for alarm, but it warrants monitoring. Delayed closure could potentially indicate underlying conditions like hypothyroidism or certain genetic disorders. Again, consulting your pediatrician is vital for proper assessment and diagnosis.

When Does the Posterior Fontanelle Close?

The posterior fontanelle is smaller and typically closes much earlier than the anterior fontanelle. This usually happens between two and three months of age. Similar to the anterior fontanelle, some variation is normal.

What if the Posterior Fontanelle Closes Early or Late?

Significant deviation from the typical closure timeframe (2-3 months) should be brought to your pediatrician's attention. While usually not a serious issue, early or late closure can, in rare instances, be associated with underlying health problems. Your doctor can assess your child's overall development and determine if further investigation is needed.

Assessing Your Baby's Fontanelles: Signs to Look For

Regularly checking your baby's fontanelles can help identify any potential concerns. Here's what to look for:

Bulging Fontanelle: A bulging fontanelle could be a sign of increased intracranial pressure, which requires immediate medical attention. This can be caused by infections like meningitis or other serious conditions.
Sunken Fontanelle: A sunken fontanelle might indicate dehydration. Ensure your baby is adequately hydrated and seek medical advice if dehydration persists.
Unusual Shape or Size: Significant deviations from the normal shape or size of the fontanelles should be evaluated by a medical professional.

When to See a Doctor About Your Baby's Fontanelles

It's crucial to contact your pediatrician if you notice any of the following:

A bulging or sunken fontanelle.
Early or late closure of the fontanelles (outside the typical ranges).
Any concerns about your baby's head shape or size.

Remember, while fontanelle closure timelines provide a general guideline, individual variations are common. Regular check-ups with your pediatrician are essential for monitoring your baby's overall health and development. Don't hesitate to reach out with any questions or concerns. Your pediatrician is your best resource for ensuring your baby's well-being.

Disclaimer: This article is for informational purposes only and should not be considered medical advice. Always consult with your pediatrician or healthcare provider for any concerns regarding your baby's health.