Fontanelle: Definition, Types, Closure, Care Tips, and Indicators of Possible Baby Health Problems

Babies are born with soft spots on their heads.

These soft, open areas of the skull are called fontanelles. If you don’t have much experience with newborns, soft spots can make you nervous, but they are easy to care for and usually close properly on their own.

A fontanelle is an opening in a baby’s skull where the bones of the skull have not yet grown and joined.

Fontanelles have two main functions:

  • Birth: Fontanelles allow the bones of the skull to move so that the baby’s head can change shape during delivery. The birth canal is narrow and the movement of the bones helps the baby’s head pass through.
  • Growth: A newborn’s head is small, but grows rapidly during the first two years of life. The spaces between the bones of the skull leave room for the rapid expansion of the brain and head.

The types

Most people know about soft spots on the top of a baby’s head, but there is more to it than that.

A newborn actually has six of them:

  • Anterior fontanel : There is an anterior fontanel on the top of the head. It is the fontanel that most people know as “the soft spot.” It is the largest of the fontanelles. At birth, the average size of the anterior fontanelle is about an inch in diameter (2.1 centimeters), but it can be larger or smaller.
  • Posterior fontanel : There is a posterior fontanel at the back of the baby’s skull. This small opening is shaped like a triangle and is usually less than ½ inch (1 centimeter) at birth.
  • Sphenoid fontanelles: There are two of these, one on each side of the head. They are placed towards the front of the skull near the temples.
  • Mastoid fontanelles : There are also two mastoid fontanels. There is one on each side of the head. They are towards the back of the skull behind the ears.

When they close

The bones of the skull are not completely sealed during childhood because the brain and body still need room to grow.

However, once the bones grow to the point that they fill the open space and can no longer be felt by doctors, the fontanelles are considered closed.

Fontanelles do not all close at the same time. The process can take two years or more.

The six fontanelles close in this order:

  • Later : between six weeks and three months.
  • Sphenoid: at six months
  • Mastoid : between six and 18 months.
  • Previous : It begins to close at six months and can no longer be felt between 18 months and two years.

The above list is a range of average closing times. A fontanel may close sooner or later and remain normal.

Care tips

Taking care of your baby’s fontanels involves learning what to look for and understanding what is normal. These are some of the things you should know.

Your baby’s fontanel should be flat against his head. It should not look like it is swollen and bulging or sunken in your child’s skull.

When you gently run your fingers across the top of your child’s head, the soft spot should feel smooth and flat with a slight downward curve.

When your child is crying, vomiting, or lying down, the fontanelle may look raised or as if it is bulging. As long as it’s back to normal once the baby is upright and calm, that’s fine and it’s not a really bulging fontanel.

Sometimes the fontanelle may appear to be pulsating. It is the baby’s pulse visible at the fontanelle and moves with the heartbeat. You can see it more easily if the baby does not have much hair or if his hair is very light. It may seem strange or scary, but it is normal.

You can be gentle, but you shouldn’t be afraid to touch or care for your child’s head. There may be a space between the bones, but a strong membrane over the opening protects the soft tissue and the brain.

So you can:

  • Touch your baby’s head.
  • Wash his head and scalp.
  • Use a baby brush or comb on your hair.
  • Put on a cute headband.
  • Let your other children hold and touch the baby (with supervision).


Fontanelles can give you clues about your child’s health. Here’s what some changes to the weak point might mean:


It is normal for the fontanelle to curve slightly inward. But, if it sinks into your baby’s head, it could be a sign of dehydration. Dehydration in newborns and young children is dangerous.

It occurs when a baby does not get enough fluids, or the child is losing more fluids than they are taking in.

Your child can become dehydrated if:

  • Does not breastfeed or bottle-feed well.
  • You get sick with diarrhea, vomiting, or fever.
  • Spends too much time in a hot environment and overheats.

Other signs of dehydration include not making enough urine, excessive drowsiness, irritability, dry mouth, and crying without tears. If your child shows signs of dehydration, call the doctor in the right way.


As mentioned above, if a baby has a slightly raised fontanel when he is crying, it does not necessarily mean that something is wrong.

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

A bulging fontanel could mean that there is a buildup of fluid or swelling in the brain. These are dangerous conditions that require immediate medical treatment.

Very big

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.

Your doctor will examine the health of your baby and the fontanelles at birth and will continue to monitor your baby as he grows.

If there is a problem, the doctor will inform you. Of course, if you are concerned about the size or closure of your baby’s fontanel, you should feel comfortable talking with the doctor.

Closes too soon

Fontanelles rarely close too early. But, if the bones of the skull come together and close too soon, it could cause some problems for the baby. Premature fusion of the skull bones is a condition called craniosynostosis.

Craniosynostosis can affect the growth of the brain and the shape of the baby’s head. It could also cause pressure to build up inside the baby’s skull. If it’s mild, you may not need treatment, but more serious conditions usually require surgery.

Sometimes the soft spots cannot be easily felt and appear closed, but are still open. The doctor will monitor your child by checking the fontanelles and measuring your baby’s head at each well-child appointment.

Head shape

Fontanelles play a role in the shape of a baby’s head. Since there is room for the bones to move, any pressure on the skull can influence its shape.

Two common head shape problems are:

Molded head

Fontanelles allow the bones of the skull to move during childbirth. The amount of time the baby’s head stays in the birth canal and the amount of pressure on the skull can determine how the baby’s head looks after delivery.

Sometimes the head appears cone-shaped or even pointed. Although it is nothing to worry about. In a few days, the baby’s head will turn into the rounder shape you expected.

Flat head

Until the fontanelles close and the bones of the skull come together, the shape of the baby’s head may change. One problem that arises is flattening of the back or side of the head called plagiocephaly.

It is from babies who are in the same position on their back or on their side. The “Back to Sleep” campaign is important and works to reduce the risk of Sudden Infant Death Syndrome (SIDS). But it can increase the chances of plagiocephaly.

If your baby sleeps on his back at night in the crib, then sits on his back in a baby carrier and car seat during the day, the back of his head will flatten out from the pressure of laying him down all the time .

To avoid pressure in one place, change your baby’s position during the day. Put your child on his back to sleep, but then give him a break when he is awake.

You can carry her in your arms or in a baby harness, let her spend a little time on her tummy, and give her things to look at that will turn her head from side to side when on her back.