Fontanelles

Parents are often afraid to touch the fontanelles, soft spots on their newborn’s head. What are they for? Is it safe to touch them?

What are fontanelles?

At birth, the bones of a baby’s head are not yet fully fused. That’s why you can feel soft spots between the skull bones. These soft spots are called fontanelles–there is no bone in these areas. They’re not exactly holes, since the bones are connected by tissue.

Your baby’s head has:

• An anterior fontanelle at the crown of the head near the front. It is diamond-shaped and approximately 2–3 cm wide.
• A posterior fontanelle at the back of the head. It is triangle-shaped and about 1 cm wide.

What are they for?

The main purpose of fontanelles is to help the baby’s progress through the birth canal during delivery. These softer areas allow the head to deform slightly, allowing the baby to emerge more easily. Not to worry, the brain is unharmed by the process and the head gradually regains its original shape. This can take anywhere from a few hours to a few days.

After birth, fontanelles allow your baby’s brain to develop properly. Brain growth is quite rapid in the first two years of life. The baby’s brain will double in size in the first year.

Should I avoid touching my baby’s fontanelles?

The fontanelles may be fragile, but you can still touch them. Just remember to be gentle. The fontanelles are made up of tissues that protect the brain well.

When you wash your baby’s hair, avoid putting too much pressure on these soft spots. You can still safely stroke the baby’s head.

Is it normal that my baby’s anterior fontanelle bulges out sometimes?

Yes, that’s perfectly normal. Fontanelles are so soft that they move as air is drawn into and expelled from the lungs. That’s why the anterior fontanelle bulges out a bit when your baby coughs or cries.

Similarly, when a baby is calm, the anterior fontanelle pulsates along with their heartbeat, or if you touch it can feel their pulse. It is also normal not to see the pulse.

Why do doctors check the fontanelles?

In your baby’s first two years, the doctor will check your baby’s head on medical checkups. This is to ensure that the fontanelles are closing normally. The doctor will also measure your baby’s head to verify normal brain growth.

Examining the fontanelles can also help the doctor detect certain health problems. Sunken fontanelles that form hollows may indicate dehydration. Enlarged, bulging fontanelles may indicate a problem caused by increased cranial pressure (e.g., infection, tumor, blood clot, or hydrocephalus). Such cases are quite rare, however. A large skull does not necessarily indicate a problem.

At what age do the fontanelles close?

Over time, the skull bones join up and fuse together. The posterior fontanelle at the back of the baby’s head closes first, when the baby is about 2 months old. The anterior fontanelle, towards the front of the head, takes a bit longer. It closes a little at a time between the ages of 9 months and 2 years.

Fontanelle closure may occur at slightly different times from one child to the next. If the fontanelles close earlier and you notice that your baby’s head is malformed, however, it’s good idea to see a doctor.

Things to keep in mind

• Fontanelles are soft spots on a baby’s head that disappear when the skull bones close.
• It is safe to gently touch your baby’s fontanelles.
• When your baby cries, it’s normal for the anterior fontanelle to swell slightly.

Scientific review: Dr. Jean-Philippe Blais, family physician specializing in perinatal care Research and copywriting:The Naître et grandir team Updated: October 2023

Photo: GettyImages/GrapeImages