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Key points
- Fontanelles allow the brain to grow.
- You cannot harm your baby by touching the fontanelle, stroking his head or washing his hair.
- The posterior (back) fontanelle closes around 2-3 months of age. The anterior (front) fontanelle closes between 12-18 months of age.
- Early or late closing of the fontanelles can be a sign of other conditions. This is why medical professionals check whether it is open or closed.
Most parents have heard of a baby’s ‘soft spot’ or by its more popular name, the fontanelle. Babies have four fontanelles, although it is the two main ones – the front and the back – that are most prominent.
Your child’s head
Newborn babies have five large bones in their head (skull) that are separated by a special type of connective tissue, called sutures. These toys work like a seam, helping the baby’s head move and mold as it is born. They also allow for brain development and rapid growth in childhood.
The bones in a baby’s skull are soft and ‘unfused’ in the early months, so there are spaces between individual bones. These spaces are made up of tough connective tissue, called fontanelles.
Where is my child’s fontanelle?
Hold the center, top of your child’s head, ½ way between their ears. You will feel a soft spot between their bones – this is the fontanelle. The nasal cavity is diamond-shaped and is between 0.6 – 3 cms, although on average, most babies have a nasal cavity that is about 2 cm long.
You may also feel a small soft spot under their head. This is the posterior fontanelle. Usually, it is smaller than the front, about 0.5 cm.
Fontanelle feels warm, soft and smooth. You may feel your fingers tingle when you touch your baby’s fontanelle – this is normal and nothing to worry about.
Some babies have more prominent fontanelles than others. When a baby has light or fine hair, it is easier to see his fontanelle than babies with dark hair.
What exactly is a fontanelle?
The word fontanelle comes from the French word Fontaine, which means spring. It is understood that this is due to the place where the spring is located on the ground or the rock.
Fontanelles are a type of hard membrane that fills the space between the bones of a baby’s skull.
Why do babies have fontanelles?
The fontanelles play an important role because they allow the expansion and adjustment of the baby’s skull during birth. As the child’s brain grows and develops, it is important that it is not restricted. The nerves and muscles between the bones of the skull allow the baby’s head to grow.
Can I hurt my baby by touching their fontanelle?
No, you cannot harm your baby by touching their fontanelle. As long as you are gentle, it is good to rub their head, wash their hair and even their head. You may notice your baby’s fontanelle moving (rising and falling), as if in sync with their heartbeat.
The membrane that covers the fontanelles is very tough and difficult to penetrate. Although often referred to as soft spots, fontanels are naturally designed to be strong and protective.
When your child is examined by health professionals, you will see that they will touch your child’s fontanelles. In fact, looking at the fontanelle is so common, it is often called “Paediatrician’s handshake”.
They will be checking to see if the fontanelles are still open, their size and if they feel flat, swollen or depressed. Sometimes the health can be influenced by the look and feel of the baby’s fontanelles. If you don’t know, ask what they are looking for.
Your child’s doctor will also measure your child’s head size to determine the size of his head. In addition, looking at their head, fontanels and head circumference can provide information about a child’s growth and development.
When does the fontanelle close?
Every child is unique and there are differences in the ages at which the fontanelles close.
However, there are middle ages when the closure of the fontanelles is expected:
- Normally, the posterior fontanelle closes 2-3 months after birth.
- The smaller pair closes between 6-18 months after birth.
- The anterior (front) fontanelle closes between 12-18 months after birth.
What can cause a child’s fontanelle to close early?
There are a few things that can cause early closure of the fontanelle. More information:
- Hyperthyroidism – excessive functioning of the thyroid gland.
- Craniosynostosis – a problem where one or more of the cords in the child’s skull fuse too quickly. This happens before the baby’s brain is fully developed and there is no flexibility for the brain to grow.
What can cause a baby’s fontanelle to be slow to close?
There are several reasons why a baby’s fontanelle may not close, or may be delayed. Sometimes the delay in closure is due to health reasons, usually:
- Congenital hypothyroidism (low thyroid function).
- Down syndrome.
- Increased energy within the brain.
- Rickets.
- A natural tendency to have a big head.
What does inverted fontanelle mean?
Sometimes the baby’s fontanelle is lower than the round tip – this means that it is sunken or depressed. If the child is well and healthy and has no problems with their development, this may be a normal difference. However, if the child is sick and/or vomiting, it could be a sign of dehydration.
Some symptoms of dehydration include:
- Fewer wet nappies.
- Feeling sleepy and unwilling to eat or play.
- Skin that is looser than normal is often not as ‘lastic’.
What does bulging fontanelle mean?
Swelling of the fontanelle can be a sign of meningitis or encephalitis. All of these are very difficult and there are other symptoms that are also present.
If you are concerned about your child’s fontanelles…
See a doctor and talk to your child if you are worried. If you notice that your child is dehydrated, keep a record of his intake and the number of wet and dirty diapers. At least six or more wet spots in a 24-hour period is one sign of adequate hydration.
Tell your child to see a doctor right away if his fontanelle is bulging or sunken.
About the Author:
Written by Nourish Baby and Jane Barry. Jane is fully qualified in paediatrics, immunisation, midwifery and pediatric nursing. She holds a Bachelor’s Degree in Applied Science (Nursing) and has approximately 35 years of pediatric health nursing experience. She is a member of a number of professional associations including AHPRA, The Australasian Medical Writer’s Association and the Australian College of Children and Young People’s Nurses.
References
About the fontanelle Pregnancy and Baby (pregnancybirthbaby.org.au)
Anatomy, Head and Neck, Fontanelles – StatPearls – NCBI Bookshelf (nih.gov)
Articles on child health | Child Health Queensland
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