What is a fontanelle?
A fontanelle is a ‘soft spot’ of a newborn baby’s skull. It is a unique 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.
If you touch the top of your baby’s head you can feel a soft spot in between the bones — this is a fontanelle.
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 in the first years of life.
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, and 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 2 months old. The anterior fontanelle can close any time between 4 and 26 months of age. Around 1 in every 2 babies will have a closed fontanelle by the time they are 14 months old.
Can I touch my baby’s fontanelles?
Yes, you can gently touch your baby’s fontanelles. If you run your fingers softly along your baby’s head you are can probably feel them. Your doctor will touch your baby’s fontanelles as part of their routine medical examination. There is no need to be concerned or worried about touching your baby’s fontanelles as long as you are gentle.
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 — this is normal. If a fontanelle changes, or feels different to how it usually does, show your doctor or midwife as it may be a sign that your baby’s health may need to be checked.
If you notice that your baby’s fontanelles are low or sunken, your baby may be dehydrated.
However, you may notice other signs of dehydration in your baby before their fontanelles becomes sunken.
Other signs of dehydration include:
- having fewer wet nappies
- not feeding well
- loosing fluids from vomiting or diarrhoea
- perspiration (or sweating) in very hot weather
- being less alert or floppy
A bulging or swollen fontanelle may be a sign of a number of serious but rare conditions including meningitis or encephalitis (infections in the brain), cerebral haemorrhage (bleeding in the brain), hydrocephalus, an abscess or another cause of increased pressure in the brain.
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. Your baby may have 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.
If you notice that your baby’s fontanelles seem to have closed early, if you can feel a ridge along your baby’s skull, or if you think that your baby’s head has an unusual shape, take your baby to see their GP or paediatrician.
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 thyroid hormones from birth), Down syndrome, increased pressure inside the brain, rickets and familial macrocephaly (a genetic tendency to have a large head).
If one or both of your baby’s fontanelles haves not closed by the time they are 2 years old, speak to your GP or paediatrician.
Who should I contact if I have concerns about my baby’s fontanelles?
If you have any concerns about your baby’s fontanelles you should make an appointment to see your child health nurse, GP or paediatrician.
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.
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Last reviewed: February 2022