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About the fontanelle

7-minute read

Key facts

  • Fontanelles are soft spots on your baby's head where the skull bones have not yet completely fused together.
  • Fontanelles are completely normal and important for brain and skull development.
  • The fontanelles should be completely closed by the time your baby is 26 months old.
  • It's safe to gently touch your baby's fontanelles.
  • If your baby's fontanelles are sunken or bulging, seek urgent medical advice.

What is a fontanelle?

If you touch the top of your baby's head you can feel a 'soft spot' in between the bones — this is a fontanelle. It is a special feature that is important for the normal growth and development of your baby's brain and skull. Your health team will check your baby's fontanelles during routine visits.

A newborn baby's skull is made up of sections of bone, known as plates, that are joined together by fibrous joints called sutures. The sutures provide some flexibility and allow your baby's head to narrow slightly as it travels through the birth canal. The sutures also enable your baby's head to grow rapidly in the first years of life.

Diagram showing the fontanelles of a baby's skull.
Illustration showing the anterior and posterior (front and back) fontanelles of a baby's skull.

There are 2 fontanelles on your baby's skull. These are the skin-covered gaps where the skull plates meet. The anterior fontanelle is at the top of your baby's head. The posterior fontanelle is located at the back of your baby's head.

When will my baby's fontanelles close?

The posterior fontanelle usually closes by the time your baby is about 2 months old. The anterior fontanelle can close any time between 4 and 26 months of age. The anterior fontanelle tends to close earlier in male than in female children.

Can I touch my baby's fontanelles?

Your doctor will touch your baby's fontanelles as part of their routine medical examination. If you run your fingers softly along your baby's head you can probably feel them. There is no need to be concerned or worried about touching your baby's fontanelles, if you are touching them gently.

What does a normal fontanelle look like?

Your baby's fontanelle should feel soft and flat. If you softly touch a fontanelle, you may at times feel a slight pulsation due to blood flow in the blood vessels around the brain — this is normal. If your baby's fontanelle changes, or feels different to how it usually does, show your doctor or midwife, as it may be the sign of a health problem.

Sunken fontanelle

If you notice that your baby's fontanelles are low or sunken, your baby may be dehydrated.

However, you will usually notice other signs of dehydration in your baby before their fontanelles becomes sunken.

Other signs of dehydration include:

Bulging fontanelle

A bulging or swollen fontanelle may indicate rare but serious conditions including:

If you think that your baby's fontanelles are bulging or sunken, seek medical advice immediately.

What if a fontanelle closes too soon?

Your baby's fontanelles may close early. This can happen for several reasons, including hyperthyroidism (high levels of the thyroid hormone) or hyperparathyroidism (high levels of parathyroid hormone).

Another cause of early fontanelle closure is a condition known as craniosynostosis. Craniosynostosis occurs when one or more of the fibrous joints (sutures) between the bone plates in a baby's skull fuse too early, before the brain has finished growing. As the brain continues to grow, it pushes on the skull from the inside but cannot expand into the closed over area. This causes the skull to have an unusual shape.

Take your baby to see their doctor or paediatrician if:

  • you think that your baby's fontanelles seem to have closed early
  • you can feel a ridge along your baby's skull
  • you think that your baby's head has an unusual shape

What if a fontanelle doesn't close?

Your baby's fontanelles may not close on time for several reasons.

Common reasons for delayed fontanelle closure include:

  • congenital hypothyroidism (low levels of thyroid hormones)
  • Down syndrome
  • increased pressure inside the brain
  • rickets
  • familial macrocephaly (a genetic tendency to have a large head)

When should I see my doctor?

If you have any concerns about your baby's fontanelles, see your doctor, child health nurse or paediatrician.

If one or both of your baby's fontanelles haves not closed by the time they are 2 years old, speak to your doctor or paediatrician.

Resources and support

The Pregnancy, Birth and Baby video call service allows you to speak face-to-face with a maternal child health nurse. Video call is a free service and is available from 7am to midnight (AET), 7 days a week (including public holidays).

Speak to a maternal child health nurse

Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available 7am to midnight (AET), 7 days a week.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: November 2023

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