Baby Fontanelles: Everything Parents Need to Know About Soft Spots

One of the most startling things about holding a newborn for the first time is feeling the soft, slightly pulsing spot on the top of their head. Many new parents hold their babies nervously at first, worried about this seemingly vulnerable area. Understanding what fontanelles are, why they exist, and what normal looks like will go a long way towards easing that anxiety.

What Are Fontanelles?

Fontanelles (also spelled fontanels) are the gaps between the bones of your baby's skull where the bones have not yet fused together. At birth, a baby's skull is made up of several separate bony plates connected by fibrous tissue called sutures. The fontanelles are the wider gaps at the junctions where multiple bones meet.

A human skull that is already fused would never fit through the birth canal. The separation between skull bones allows the head to change shape during delivery — a process called moulding — and then return to a more rounded shape over the days following birth.

How Many Fontanelles Does a Baby Have?

Babies are born with six fontanelles in total, though most parents only ever notice two.

The anterior fontanelle is the largest and most noticeable — the soft spot at the top of the head. It is diamond-shaped and typically measures between 2 and 3 centimetres across, though there is natural variation. It usually closes between 12 and 18 months of age, though anywhere between 9 and 24 months is within the normal range.

The posterior fontanelle is at the back of the head, where the two parietal bones and the occipital bone meet. It is much smaller — often smaller than a fingertip — and typically closes by six to eight weeks of age. Many parents never notice it.

The other four fontanelles — the paired sphenoidal and mastoid fontanelles on either side of the head — are small and close early, often before or shortly after birth.

What Is Normal?

A slight pulsing. This is completely normal. The fontanelle overlies blood vessels, and you can sometimes see or feel the pulse of blood flowing through them. It can look alarming, but it is simply the normal rhythm of your baby's circulation visible through this soft area.

A slightly dipped appearance when upright and calm. When a baby is sitting or being held upright and is calm, the anterior fontanelle often appears slightly sunken or indented. This is normal and reflects normal intracranial pressure in an upright position.

Bulging briefly during crying. The fontanelle may bulge outward when a baby is crying or straining. The increased pressure of crying temporarily raises the pressure inside the skull. This is normal and will resolve as soon as the baby calms down.

Being flat or slightly firm when lying down. When a baby is lying flat, the fontanelle often feels firmer and may appear slightly fuller than when upright. This is normal.

Variations in size. Fontanelles vary considerably between babies. A larger anterior fontanelle does not indicate a problem on its own, though it will be monitored as part of routine health checks.

When to Seek Urgent Help

Knowing when a fontanelle is telling you something important is essential knowledge for every parent.

A sunken fontanelle — one that appears markedly indented and feels hollow — is a sign of dehydration. In a young baby, dehydration can progress quickly. If you notice a sunken fontanelle alongside other signs of dehydration (reduced wet nappies, dry mouth, sunken eyes, a high-pitched cry, unusual drowsiness), you should seek urgent medical attention. Call 999 or go to A&E if your baby is unwell.

A persistently bulging fontanelle — one that is visibly raised and tense when your baby is calm and upright — is a medical emergency. It can indicate raised intracranial pressure, which may be caused by meningitis, encephalitis, bleeding inside the skull, or another serious condition. Do not wait to see if it resolves. Call 999 immediately.

The key distinction is: a fontanelle that bulges when a baby cries and then returns to normal is not a concern. A fontanelle that remains bulging, tense, and raised when the baby is calm and upright is an emergency.

Can You Touch the Fontanelle?

Yes. Normal daily handling — washing your baby's head, stroking their hair, resting a hand gently on their head — will not harm the fontanelle. The fibrous membrane covering it is tough and resilient. You cannot injure your baby by touching it gently.

You should, of course, avoid any forceful pressure, but normal parental handling poses no risk. Many parents spend months unnecessarily avoiding the top of their baby's head, which is not necessary.

When Does the Fontanelle Close?

The anterior fontanelle typically closes between 12 and 18 months of age. At your baby's routine health checks, the midwife or health visitor will check the fontanelle as part of their general assessment. If it is closing earlier than expected — before six months — or later than expected, they may arrange further assessment, but early or late closure on its own is often benign and may simply reflect normal variation.

A fontanelle that is still open beyond 24 months is worth discussing with your GP, as it can occasionally be associated with conditions such as hypothyroidism or rickets, both of which are treatable.

The Bottom Line

Your baby's fontanelles are a normal and important feature of early development. The soft spot on the top of their head is resilient enough for ordinary handling, normal to pulse gently, and normal to dip slightly. What you are watching for is a persistently bulging, tense fontanelle in a calm baby, or a markedly sunken fontanelle alongside signs of illness — both warrant urgent attention.