What To Know About the Soft Spots on Your Baby's Head

The "soft spots" (aka fontanelles) on your baby's head are the spaces between the five major bones of their skull. The spaces exist because a newborn's skull has not yet fused together, which allows them to maneuver through the pelvis during vaginal birth. The fontanelles feel soft to the touch.

Babies are born with six fontanelles that will slowly close over the first year or so. The largest one, located between the forehead and the crown of the head, is called the anterior fontanelle. This fontanelle can be an important health indicator.

Learn more about the soft spots on your baby's head, how to care for them, and when to call a health care provider.

What Are the Soft Spots on a Baby's Head?

A fontanelle, or a soft spot, is an opening in a baby’s skull where the bones have not yet grown together. Although they may seem like undeveloped areas of your baby's head, fontanelles are actually a critical part of normal infant development. They serve two important roles for your child. First, they aid in their birth and later, they allow for rapid growth.

Here is what you need to know about these two roles:

• Birth: By leaving space for the bones of the skull to move during delivery, the fontanelles allow your baby's head to fit through the narrow birth canal without damaging the brain.
• Growth: A baby's head grows more quickly over the first two years than at any other time in their life; the spaces between the skull bones leave the room needed for rapid brain growth during this period. 

Types of Fontanelles

Most people know about the large soft spot on the top of a baby’s head, but it's not the only one. A newborn has six fontanelles:

• Anterior fontanelle: Located on the top of the head, this diamond-shaped fontanelle is the one that most people know as "the soft spot." It measures approximately 1 to 3 centimeters at birth, but can be larger or smaller.
• Posterior fontanelle: This smaller opening at the back of the baby’s skull is triangular in shape. It usually measures less than 1/2 centimeter at birth.
• Mastoid fontanelles: This type of fontanelle is a paired structure, meaning there are two. These are located at the intersection of the temporal, parietal, and occipital bones, found towards the back of the head.
• Sphenoid fontanelles: Like mastoid fontanelles, this type of fontanelle is also paired, located on either side of the skull.

When Do Fontanelles Close?

The skull bones don't completely close during childhood because the brain still needs room to grow. However, once the bones grow to the point that they fill in the open spaces, the fontanelles are considered closed.

A baby's fontanelles close in the following order:

• Posterior: Between 1 and 2 months
• Anterior: Between 13 and 24 months 
• Mastoid: Between 6 and 18 months
• Sphenoid: Around 6 months after birth

The list above is a range of average closure times. A fontanelle can close earlier or later and still be "normal" and healthy.

How To Care for Your Baby's Fontanelles

While caring for your baby’s fontanelles isn't complicated, the soft spots make many new parents nervous. Rest assured that a health care provider will check your baby’s fontanelles at birth and again at their first visit to the pediatrician.

This monitoring will continue whenever a doctor, midwife, or nurse examines your child at well-baby visits, and you can also check your baby's soft spot at home. While there isn’t anything special you need to do to care for your baby's fontanelles, it’s good to know what to look for so you can feel more confident in caring for your new baby.

Here are some of the things to know: 

• Your baby’s fontanelles should look flat against their head; they should not look swollen and bulging or sunken down into your child’s skull. 
• When you gently run your fingers over the top of your child’s head, the spot should feel soft and flat with a slight inward curve.
• When your child is crying, vomiting, or lying down, the anterior fontanelle may look raised or like it’s bulging. As long as it goes back to normal once the baby is upright and calm, there is no cause for concern. 
• You may notice that the fontanelles seem to be pulsating in rhythm with your baby's heartbeat. This is also completely normal. 

Although the soft spot is a space between the skull bones, a tough membrane over the opening protects the soft tissue and the brain inside. You don't have to be worried about everyday contact, such as:

• Touching your baby’s head, even on their soft spot
• Washing their hair and scalp
• Using a baby brush or comb on their hair  
• Putting on a cute hat or headband 
• Allowing your other children to hold and touch the baby (with supervision)

As with all other aspects of caring for your infant, be sure to handle your baby and their fontanelles gently. With practice, you'll develop more confidence. As long as you don't put pressure on your baby's soft spots, you don't need to worry that you're hurting them.

Sunken Fontanelles and Other Concerns

Your baby's fontanelles can give you clues about your child’s health. Here are what some changes in their fontanelles could mean.

Sunken fontanelles

It is normal for a fontanelle to have a slight inward curve. However, a fontanelle that sinks down into your baby’s head could be a sign of dehydration, which happens when they aren't drinking enough fluids or are losing more fluids than they're taking in.

Your baby can become dehydrated if they: 

• Are having problems with breastfeeding or bottle-feeding
• Have diarrhea, vomiting, or fever
• Spend too much time in a hot environment and become overheated

Other signs of dehydration include not producing enough urine, excessive sleepiness, irritability, dry mouth, and crying without tears.

Dehydration in newborns and young children is considered a medical emergency. If your child is showing signs of dehydration and/or you notice that their fontanelles are sunken, call your pediatrician right away.

Bulging fontanelles

As mentioned above, it is normal for a baby's fontanelle to be slightly raised when they are crying or vomiting. Both of these actions briefly increase the pressure inside the skull.

However, if the baby’s fontanelle continues to bulge when the baby stops crying, or it feels swollen and hard when the baby is resting, it could be a sign of a problem.

A bulging fontanelle could mean that there is a buildup of fluid or swelling in the brain. These are dangerous conditions that require immediate medical treatment. If you notice that your baby's soft spot feels hard or is bulging, call your pediatrician.

Enlarged fontanelles

A soft spot that is abnormally large or does not close within the expected time frame can be a sign of certain medical conditions such as hypothyroidism, Down syndrome, or rickets (a condition caused by vitamin D deficiency).

Your pediatrician will be monitoring your baby's fontanelles in every checkup from birth until they are closed. If you are worried about their size or appearance, however, be sure to voice your concerns.

Fontanelles that close too soon

It is possible, although rare, for the fontanelles to close too early. Sometimes the soft spots cannot be felt easily and may seem closed, but they are still open.

Premature fusing of the skull bones is a condition called craniosynostosis. Both the brain’s growth and the shape of the baby’s head can be affected by this condition.

Another result of the skull bones fusing too soon can be pressure building up inside the baby’s skull. While the Centers for Disease Control and Prevention (CDC) report that very mild cases of craniosynostosis may not need treatment, in many cases, surgery is required to relieve the pressure and allow the brain to grow normally.

How Fontanelles Affect a Baby's Head Shape

The fontanelles play a role in the shape of a baby’s head. Since there is space for the bones to move during the first year of life, any pressure on the skull can influence its shape. Two common head shape issues in babies include molded head and flat head syndrome. 

Molded head

The length of time a baby’s head stays in the birth canal and how much pressure there is on the skull can determine what the baby’s head looks like after delivery.

If you had a long or difficult vaginal delivery, your baby's head may appear cone-shaped or even pointy, a condition known as caput succedaneum. Within a few days, though, it will turn into the more rounded shape that you were expecting.

Flat head

Until the fontanelles close and the bones of the skull join together, the shape of the baby’s head can change.

If your baby lies on their back to sleep and sits in a car seat for long stretches of time while awake, the back of their head can become flat, a condition known as positional plagiocephaly.

The “Safe to Sleep” campaign, formerly known as the "Back to Sleep" campaign, advises that infants should sleep on their backs to lower the risk of sudden infant death syndrome (SIDS). However, it can increase the chances of plagiocephaly.

To prevent prolonged pressure on one area of your baby's head, change their position frequently during the day. Place your child on their back to sleep, but then give the back of their head a rest when they're awake.

You can try some of these positions during the day when your baby is awake to provide relief for the back of your child's head:

• Carry your baby in your arms
• Use an infant sling, wrap, or carrier
• Let them spend time on their tummy
• Give them things to look at that will turn their head from side to side when they're on their back