You may have noticed the soft, pulsating spot on top of your baby's head. It can feel alarming to touch, but the fontanelle is completely natural and serves an important purpose.
Fontanelles are one of nature's clever solutions. They make birth possible and give the brain room to grow. Here is everything you need to know about your baby's soft spots.
What is the fontanelle?
A baby's skull is not one solid bone but consists of several bony plates connected by fibrous tissue. The fontanelles are the openings between these plates.
Babies have several fontanelles, but two are the most noticeable:
Anterior fontanelle (the large one):
- Located on top of the head, slightly forward of center
- Diamond-shaped and about 2–3 cm wide at birth
- The one you can most easily feel and see
- Typically closes between 12 and 18 months of age
Posterior fontanelle (the small one):
- Located at the back of the head, where the back meets the crown
- Triangular and much smaller (about 0.5–1 cm)
- Harder to feel
- Closes as early as 2–3 months of age
Did you know? Babies actually have six fontanelles at birth. The four extra ones sit on the sides of the head and are so small they are rarely noticed. They close quickly during the first months of life.
Why do babies have fontanelles?
Fontanelles serve two important functions:
1. Birth
During delivery, the skull's bony plates can slide over each other and adapt to the birth canal. This is why many newborns' heads look slightly elongated or molded in the first few days. This is completely normal and resolves within a few weeks.
2. Brain growth
A baby's brain grows enormously in the first year of life — it almost doubles in size. The fontanelles provide room for this growth. Without them, the skull would limit brain development.
At well-child visits, your pediatrician or healthcare provider measures your baby's head circumference to make sure growth is proceeding normally.
What does a normal fontanelle look and feel like?
It is completely normal for the fontanelle to:
- Pulsate gently in rhythm with the heartbeat — this is simply blood flowing through nearby vessels
- Be flat or slightly curved when the baby is resting quietly
- Bulge slightly when the baby cries, coughs, or strains (and flatten again afterward)
- Feel soft to the touch — you can feel the fibrous tissue beneath the skin
It is also normal for fontanelle size to vary from baby to baby. Some babies have a large fontanelle, others a smaller one. Size alone says little about a baby's health.
Is it safe to touch the fontanelle?
Yes. The fontanelle is well protected by a thick layer of fibrous tissue beneath the skin. You will not harm your baby by gently washing the head, brushing the hair, or stroking over the soft spot.
Normal care and handling is completely safe:
- You can wash the head during bathing
- You can gently brush away any cradle cap
- You can stroke your baby's head
- Hats and headbands are not dangerous
There is no need to fear touching the fontanelle during normal care. It is much stronger than it feels.
Cradle cap (seborrheic dermatitis) is common in infants and can occur over the fontanelle. You can gently massage with baby oil and brush away the flakes. The fontanelle handles this just fine.
When does the fontanelle close?
The fontanelles close gradually as the bony plates grow together:
| Fontanelle | Closing time |
|---|---|
| Posterior fontanelle | 2–3 months |
| Anterior fontanelle | 12–18 months |
There is a wide range of normal. Some babies have a closed anterior fontanelle by 9 months, while in others it does not fully close until 24 months. Both can be completely normal.
Your pediatrician checks the fontanelle at regular well-child visits. If it closes too early or too late, this will be followed up.
Early closure (craniosynostosis)
If the fontanelle closes too early, it can in rare cases indicate craniosynostosis — a condition where the skull bones fuse too quickly, which can restrict brain growth.
Signs may include an unusual head shape or head circumference not growing as expected. This is rare and is usually picked up at routine well-child checks.
Late closure
A fontanelle that remains open longer than usual is rarely a cause for concern on its own. It can be a family variation. In some cases it may be linked to low vitamin D levels (rickets) or thyroid problems. Your doctor will assess this alongside other measurements.
Warning signs: When should you be concerned?
The fontanelle can provide important information about your baby's health. Here is what to watch for:
Sunken fontanelle
A fontanelle that sinks noticeably inward can indicate dehydration. This is an important warning sign, especially if your baby:
- Has had vomiting or diarrhea
- Is drinking less than usual
- Has fewer wet diapers
- Seems lethargic or unusually tired
Contact your doctor if the fontanelle is clearly sunken, especially in combination with other signs of dehydration such as fewer wet diapers, dryness in the mouth, or your baby seeming unusually limp. Infants under 3 months with signs of dehydration should be assessed promptly.
Tense or bulging fontanelle
A fontanelle that bulges outward and feels tense when the baby is calm (not crying) can indicate increased pressure inside the head. This may be caused by:
- Infection (such as meningitis)
- Accumulation of fluid
A fontanelle that bulges a little during crying or straining is completely normal. It is the persistent, tense bulge at rest that is a warning sign.
Call emergency services if your baby has a tense, bulging fontanelle along with:
- High fever
- Irritability or crying that cannot be soothed
- Stiffness in the neck
- Lethargy or reduced consciousness
- Vomiting
This may indicate meningitis and requires immediate evaluation.
Myths about the fontanelle
Myth: You can damage the brain by touching the fontanelle
Fact: The fontanelle is protected by thick fibrous tissue. Normal touching, washing, and grooming is completely safe.
Myth: A large fontanelle means something is wrong
Fact: Fontanelle size varies considerably between babies. Size alone says nothing about a baby's health.
Myth: The fontanelle must be closed by 12 months
Fact: The normal range is 9–24 months for the anterior fontanelle. Healthcare providers monitor this, but it is rarely a cause for concern.
Myth: Pulsation in the fontanelle is dangerous
Fact: Pulsation is completely normal and is caused by blood flow. It simply shows that the heart is beating as it should.
The fontanelle at well-child visits
At well-child check-ups, your healthcare provider examines the fontanelle as part of the routine assessment. They evaluate:
- Size — whether the fontanelle is appropriate for the baby's age
- Tension — whether it feels normal or tense
- Shape — whether it is flat, bulging, or sunken
- Head circumference — whether the head is growing as expected
Head circumference is measured at every check-up visit and plotted on a growth chart. You can track your baby's growth between visits using Babysential's growth tools.
Frequently asked questions
Can my baby sleep with their head to one side without damaging the fontanelle?
Yes. Babies should always be placed on their back to sleep (to prevent SIDS), but the head resting slightly to one side is completely safe. Alternate which side the head tilts toward to avoid flat head syndrome (positional plagiocephaly).
What should I do if my baby falls and hits the fontanelle?
Minor accidents happen. The fontanelle can withstand normal bumps. Contact your doctor if your baby becomes unusually limp, vomits, or you see swelling, bruising, or a change in the fontanelle after a fall.
Does my baby feel me touching the fontanelle?
Your baby feels touch on the fontanelle the same as any other touch on the head. It does not hurt to touch it gently.
Can the fontanelle close and open again?
No. Once the bony plates have grown together, the fontanelle is permanently closed. If you are unsure whether the fontanelle is open or closed, your healthcare provider can check at the next visit.
Is it normal for the fontanelle to pulsate?
Yes, this is completely normal. Pulsation is caused by blood flowing through vessels near the surface. You can see it most clearly when your baby is calm and relaxed.
Sources
- American Academy of Pediatrics (AAP) — Well-child visit guidelines
- WHO — Child growth standards and monitoring
- Nationwide Children's Hospital — Fontanelle information
- CDC — Safe sleep guidelines for infants