Your baby's soft spot (fontanelle)

What are soft spots on a baby's head?

Soft spots, or fontanelles, are areas on a baby’s head where the skull bones have not fully fused. These spots are covered by a tough membrane and are softer than the rest of the skull. They help the baby’s head pass through the birth canal during birth and allow room for rapid brain growth during the first year of life.

Types of fontanelles

The two most important fontanelles are:

1. Anterior fontanelle: Located on the top of the head.
2. Posterior fontanelle: Located at the back of the baby’s skull.
3. Mastoid fontanelles: There are two mastoid fontanelles, located towards the back of the head.
4. Sphenoid fontanelles: There are two sphenoid fontanelles, located on both sides of the skull.

When do the soft spots close?

Each soft spot closes at a different time:

• Anterior fontanelle: Between 9 and 24 months.
• Posterior fontanelle: Between 1 and 2 months.
• Mastoid fontanelles: By 12 months
• Sphenoid fontanelles: By 6 months

Caring for your baby's soft spots

Handle your baby’s soft spots with care, avoiding direct pressure. Be gentle when bathing them, washing their head, dressing them, or brushing their hair. Teach siblings to avoid touching the baby's soft spots.

Regularly monitoring your baby’s soft spots for any abnormalities in size or tension. It’s normal to see the fontanelle pulsating in rhythm with your baby’s heartbeat. Your pediatrician will examine your baby's fontanelles during routine checkups to ensure healthy development.

Abnormal fontanelles

• Sunken fontanelles may be a sign of dehydration or malnutrition. Sunken soft softs require immediate medical attention.
• Bulging fontanelles can indicate increased intracranial pressure, which could be caused by fluid build up in the brain or meningitis.
• Enlarged fontanelles may be linked to conditions such as hypothyroidism, Down syndrome, or elevated intracranial pressure.
• Craniosynostosis is a condition where one or more cranial sutures close too early, potentially resulting in abnormal head shapes and restricting brain growth.

Fontanelles and head shape

Fontanelles play a key role in shaping a baby's head by allowing the skull to mold during birth and make room for brain growth after birth. The temporary reshaping of the head as it passes through the birth canal typically resolves within a few days to weeks. A flat head, or positional plagiocephaly, can develop when prolonged pressure on one area of the skull (usually from lying in the same position for extended periods) causes a flat spot to form.

Providing plenty of tummy time during the day and alternating your baby's head position while they sleep can help gradually improve mild flattening. For sleep, always put your newborn baby on their back for safe sleep.

When to consult your pediatrician

Consult your pediatrician if you notice:

• A bulging soft spot
• A sunken soft spot
• Enlarged fontanelles
• Your child has extreme irritability, decreased feeding or alertness, or other concerning symptoms.

If you have questions about your baby's fontanelles, reach out to your local or Summer Health pediatrician for support. Summer Health is a pediatric telehealth platform offering 24/7 care, providing answers for everything from urgent concerns to everyday questions about your child’s health.