Baby Soft Spot: What the Fontanelles Are, When They Close and When to Worry

A baby soft spot is a normal gap between the skull bones that lets the head mold at birth and the brain grow, and it should feel flat and firm, with the back one closing in the first couple of months and the front one usually between about 7 and 24 months.

The first time you feel your baby’s soft spot, it can be a little unnerving. It feels like a gap, it may pulse, and it seems far too delicate to wash. The good news: a baby soft spot is completely normal, and gentle everyday handling does not hurt it.

This guide explains what fontanelles are and why babies have them, when each one usually closes, why a soft spot pulses, how to care for it, and what a sunken, bulging, early closing or late closing soft spot can mean. Every clinical point is checked against MedlinePlus, StatPearls, the AAP, the CDC and a children’s hospital.

Baby Soft Spot: The Short Answer

What Are Fontanelles (Fontanels)?

Fontanelles, also spelled fontanels, are the medical name for soft spots. MedlinePlus describes them as the open spaces between the skull bones of babies and young children, and calls them a normal part of development.

A newborn’s skull is not one solid bone. It is several plates held together by flexible seams called sutures. Where several sutures meet, there is a wider gap: that gap is a fontanelle. StatPearls, a clinical reference on the NIH bookshelf, notes that six fontanelles are present in infancy, but only two are large enough for parents to feel easily:

• The anterior fontanelle: on the top of the head, just forward of center (MedlinePlus). StatPearls calls it the largest of the six and describes it as diamond shaped. This is the one most people mean by “the soft spot.”
• The posterior fontanelle: at the back of the middle of the head (MedlinePlus). StatPearls describes it as triangular and much smaller. MedlinePlus notes it may already be closed at birth.

The other four sit at the sides of the head and are rarely noticed at home.

Why Babies Have Soft Spots

Soft spots do two jobs:

• Getting through birth: StatPearls explains that the sutures let the skull mold during birth. That flexibility helps the head fit through the birth canal.
• Making room for the brain: StatPearls adds that the open sutures allow for rapid growth and development of the brain after birth.

MedlinePlus says the skull bones generally stay separate for about 12 to 18 months before they grow together. Curious what else is changing? See how long the newborn stage lasts, newborn vision, when babies’ eyes change color and things to do with a newborn.

When Does the Soft Spot Close? Sizes and Ages

The honest answer is a range: reputable sources give slightly different numbers, and normal sizes vary widely.

StatPearls also notes that the anterior fontanelle tends to close sooner in boys. The big picture: the back soft spot is gone within the first couple of months, and the front one often closes in the second year.

You do not need to measure anything at home. Your pediatrician checks the fontanelles at well visits.

Is It Normal for the Soft Spot to Pulse?

Yes. StatPearls states that a normal soft pulsation may be felt at the anterior fontanelle. UPMC Children’s explains that you are seeing or feeling blood flowing underneath the membrane.

It is often easiest to see in babies with little hair. What matters more is how the spot looks and feels overall: flat and firm is the normal baseline (MedlinePlus).

Can You Touch or Wash the Soft Spot?

You can, gently. UPMC Children’s says holding your baby’s head, washing hair and putting on hats or hoods are all fine. The membrane over the fontanelle is tough, so a minor bump is unlikely to cause harm.

• Bath time: bathing and hair washing do not hurt the soft spot (UPMC Children’s).
• Flaky scalp: if your baby has a flaky scalp (often called cradle cap), gentle washing and soft brushing over the soft spot are fine. Ask your pediatrician if the scales spread, look red or weep.
• Hats and hoods: UPMC Children’s says hats can be used without worrying about the fontanelle.
• Helmets: a soft spot never needs a helmet. Molding helmets treat some cases of head flattening and are fitted by a specialist (AAP).

Sunken Soft Spot: A Sign of Dehydration

StatPearls says a sunken fontanelle is primarily due to dehydration, and the American Academy of Pediatrics (AAP) lists a sunken soft spot among the signs of mild to moderate dehydration. The AAP’s full list of mild to moderate signs:

• Playing less than usual.
• Urinating less often: for infants, fewer than six wet diapers a day.
• A parched, dry mouth.
• Fewer tears when crying.
• A sunken soft spot.

And these as signs of severe dehydration, on top of the ones above: very fussy, excessively sleepy, sunken eyes, cool and discolored hands and feet, wrinkled skin, and urinating only one to two times a day. The AAP says to notify the pediatrician immediately if any of these develop.

Counting wet diapers is the easiest check at home. Our guides on how much a newborn should eat and newborn poop explain what normal looks like.

Bulging Soft Spot: When It Is Normal and When It Is an Emergency

A soft spot can look fuller for a moment without anything being wrong. MedlinePlus explains that a fontanelle may look bulging while a baby is crying, lying down or vomiting, and that it should go back to normal once the baby is calm and head up.

Try this: hold your baby upright until settled, then look again. A spot that goes back to flat and firm is behaving normally.

A soft spot that stays tense or bulging when your baby is calm and upright is different. MedlinePlus says this can happen when fluid builds up in the brain or the brain swells, and that a truly bulging fontanelle needs immediate emergency care, especially with fever or excessive drowsiness. MedlinePlus lists these possible causes:

• Encephalitis (swelling of the brain, often from an infection).
• Hydrocephalus (a buildup of fluid in the brain).
• Increased pressure inside the skull.
• Meningitis (infection of the membranes covering the brain and spinal cord).

StatPearls adds bleeding, trauma and low oxygen levels to the list of things that can raise pressure inside the skull You do not need to work out the cause: a bulging soft spot in a calm, upright baby is a go-now situation, not a wait-and-see one.

Soft Spot Closing Too Early or Too Late

Early closure. The CDC describes craniosynostosis as a birth defect in which the bones of a baby’s skull join together too early. The CDC estimates it affects about 1 in 2,500 babies in the United States. The first sign is usually an abnormally shaped skull, and other signs include a missing soft spot and slow or no growth in head size over time. The CDC says it is usually diagnosed soon after birth, and that many types need surgery, usually in the first year of life, while very mild cases may not.

Late closure or a large soft spot. StatPearls lists the most common conditions associated with a large anterior fontanelle or delayed closure as achondroplasia (a form of short stature), congenital hypothyroidism, Down syndrome, increased pressure inside the skull and rickets. UPMC Children’s says a much delayed closing should be discussed with a doctor. Because typical closing ages run well into the second year, a soft spot that is still open at your baby’s first birthday is not, on its own, a reason to panic.

Flat Spots and Head Shape

A flat area on the back or side of the head is a separate issue. The AAP explains that positional skull flattening usually comes from spending a lot of time in one position, including lots of time on the back without enough tummy time. The AAP calls these changes purely cosmetic and says most do not need surgery.

Back sleeping is still the rule. Every sleep, your baby goes down on their back on a firm, flat, bare surface, with no pillows, positioners or wedges (see our safe sleep environment checklist). The AAP notes that head shaping pillows are not safe and have not been shown to work. Instead, it suggests:

• Tummy time while awake: start with short spurts and build up to about an hour a day in several sessions (AAP). See when to start tummy time, tummy time by age and, for reluctant babies, what to do if your baby hates tummy time.
• Switch it up: alternate which end of the crib your baby’s head points toward, and switch arms when you hold and feed them (AAP).
• Less time in seats: limit long stretches in car seats outside the car, bouncers, swings and carriers, which press on the back of the head (AAP).

The AAP says molding helmets may be considered for moderate or severe flattening that has not improved with other steps by about 5 or 6 months, and that a pediatrician can tell positional flattening apart from craniosynostosis, which it calls uncommon but more serious.

Related Betteroo Guides

• When to Start Tummy Time
• Tummy Time by Age
• How Long Is the Newborn Stage
• Newborn Vision
• Sleepy Newborn: When to Worry
• When Can a Baby Go in a Pool

When to Call Your Pediatrician

Trust your instincts: if the soft spot looks different and your baby does not seem like themselves, call.

Call 911 or go to the emergency room now if:

• The soft spot bulges or feels tense while your baby is calm and upright, especially with a fever or unusual drowsiness (MedlinePlus).
• The soft spot looks swollen and your baby has a fever or seems lethargic (UPMC Children’s says to call immediately).
• The soft spot is sunken and your baby shows severe dehydration signs: excessively sleepy or hard to wake, very fussy, sunken eyes, cool or discolored hands and feet, or only one or two wet diapers a day (AAP).
• Your baby is unusually sleepy, hard to wake or floppy, or seems very unwell (MedlinePlus, AAP, UPMC Children’s).

Call the pediatrician’s office the same day if:

• The soft spot looks sunken, or your baby has milder dehydration signs such as fewer than six wet diapers a day, a dry mouth or fewer tears (AAP).
• Your baby has had vomiting or diarrhea and is drinking less than usual.
• Your baby took a bump to the head and you are unsure whether they need to be seen.

Bring it up at the next checkup (or call sooner if worried) if:

• You cannot feel the front soft spot in a young baby, or the head shape looks unusual (CDC).
• The soft spot seems much larger than expected, or is still open well past the ages in the table above (StatPearls, UPMC Children’s).
• You see a flat spot that is not improving with tummy time and position changes (AAP).

This article is general education, not medical advice. Your own pediatrician’s instructions come first.

Frequently Asked Questions

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