Why Does a Baby’s Head Flatten?

Baby flat head

In 1994, pediatricians and public health groups started advising parents and caregivers to always put babies to sleep on their backs as a way to help prevent sudden infant death syndrome (SIDS). Since the start of the “Back to Sleep” campaign, the incidence of SIDS in the United States has dropped by an amazing amount: more than 50%!

This is wonderful news, but there is an unintended consequence to having babies sleep on their backs. Babies who sleep on their backs may develop a flat area on the back of their heads. The medical term for this is positional plagiocephaly, which sounds terrible, but flat-head syndrome is a rather minor problem if it develops.

First, not every baby develops a flattened area on their heads. If a flattened area does develop, it does not cause any problems with a baby’s brains or with their mental development. And the good news is that it can almost always be corrected very easily.

You can usually spot a flattened area on your baby’s head. The back of your baby’s head simply looks a bit flat either right in the center of the back of the head or on one side of the back of the head. Some babies who have a full head of hair may have a bald spot on the flat spot.

If you think your baby’s head has a flat spot or if it seems to be asymmetrical, talk to your baby’s pediatrician or healthcare professional. Although most cases of flat-head syndrome are due to babies sleeping on their backs, some cases are due to tight neck muscles that prevent a baby from moving his or her head easily. A more serious condition is craniosynostosis, where the bones of a baby’s head start to fuse together too early. Your doctor or healthcare professional can check this out and advise you.

Why Does a Baby’s Head Flatten?

A baby’s head can develop a flat spot if he or she sleeps in the same position most of the time because a baby’s skull is rather soft. The top of an adult’s skull is a solid piece of bone, but a baby’s skull is made up of six plates of bone that have not completely fused together yet. This softness allows for the baby’s head to pass through the birth canal easier and also allows for the growth of the baby’s brain. These plates start to fuse together over several years. A child’s head usually continues to grow until age 7.

Treating Flat-Head Syndrome

Flat-head syndrome that is caused by the baby’s sleeping position is easy to treat. You just make sure that you vary the position that you put the baby to sleep for naps or overnight. One night, put the baby to sleep in the crib with his or her head at the head of the crib. The next night, position the baby with his or her head at the foot of the crib. This continuing change of position helps the baby’s head because babies move their heads a bit as they sleep. They also tend to move so that they face something interesting to look at, such as a window or a door. Alternating which way the baby faces in the bed will encourage him to move his head in both directions, which in turn evens out any flattening.

Do not put the baby to sleep on his or her stomach. Also, do not use any pillows or pads in the crib with your baby.

Another way to help prevent or correct a flat head is by giving your baby supervised “tummy time.” This is time your baby spends on her stomach while you play with her. Being on their tummies allows babies to develop their arm and neck muscles since babies want to push themselves up and see what is going on around them. The slogan that promoted having babies sleep on their backs has been modified to include this tummy time. It is now “Back to Sleep, Tummy to Play.”

Another way to reduce the risk of a flattened area is to hold your baby more. Holding your baby reduces the amount of time the baby spends in the crib.

A flat area on a baby’s head will usually start to even out as the baby starts to move more and learns to sit up. If several weeks of alternating sleep positions and more tummy time don’t help your baby’s head even out, talk to your pediatrician or healthcare provider. Your baby may need physical therapy for the muscles of your baby’s neck. Another possible treatment is a helmet or headband to help reshape the head, but this is used only in rare cases.

Valerie DeBenedette
Valerie DeBenedette is an experienced health and medical writer who lives about an hour north of New York City with a dog that is smaller than her cat. Her work has appeared in magazines, newspapers, newsletters, and on websites. She is a member of the National Association of Science Writers.

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