An infant’s skull is made up of pieces of bone called plates. The connection between two plates is called a suture, and it is quite flexible in the first year of life. There are also soft spots in an infant’s skull, called fontanelles, which are openings where multiple plates come together. The flexibility provided by these features allows for the ability of the plates to compress and overlap for the trip through the birth canal. It also accommodates the rapid brain growth that is seen during the first year. Over the first year and a half of life, the fontanelles close and the sutures become less flexible.
An infant’s head is very moldable in the first year of life, and the forces on it will determine if it shapes into a typical round shape or if it develops a flat spot or other abnormal shape. Some babies are born with an oddly shaped head due to forces in utero such as not enough space from a differently shaped uterus, too little amniotic fluid, more than one baby at a time, or an extended amount of time in the birth canal. Once the baby is born, the forces that caused the abnormal head shape are no longer present, so the shape tends to improve. Other babies are born with a perfectly round head, but it becomes flattened over time due to forces caused by positioning the baby. When babies spend much more time on their backs than on their tummies and/or spend a significant amount of time in infant positioning devices, they often have pressure on the back of their head which causes the skull to flatten over time. In some rare instances, flattening of an infant’s head is due to a condition called craniosynostosis, where a suture of the skull fuses early. Your child’s pediatrician will help determine if your child needs to see a specialist to rule out craniosynostosis.
The most common cause of flattening of an infant’s skull is due to positioning. Children who lie on the back of their head too much of the day without moving will develop flatness across the back of their head. Other children may develop flatness more or only on one side of the back of their head. These children also lie on the back of their head too much of the day without moving, but are doing so with their head preferentially turned to one side. Infants who have a preference to consistently turn or tilt their head to one side should be referred to a pediatric physical therapist for evaluation. Other head shape changes that may be seen are widening or narrowing of the head, prominence of the forehead on one or both sides, asymmetrical ear alignment, and/or asymmetry in the facial features. If you notice any of these features in your infant, speak with your pediatrician to determine if they should be referred to a pediatric neurosurgeon or plastic surgeon who work with children with asymmetrical head shape.
The recommendation for babies to be positioned on their backs for sleep has helped to significantly reduce infant deaths due to SIDS and other sleep-related causes. However, there has also been a significant increase in positional skull deformities as well as increased reports of delayed achievement of milestones since that initiative was started. It was added that parents should include supervised, awake tummy time to their baby’s daily routine. Tummy time helps your baby to strengthen his muscles to become more mobile and also does not place any pressure on the back of his head.
To prevent or improve flattening of your baby’s head, it is important that she is provided with opportunities to move, unrestricted, in a variety of ways. Lay your baby on the floor to move and play on her back, tummy, and sides. Be sure to alternate sides with everyday activities such as which side you hold him for feeding or carrying and which direction you lay him down on his back in the crib. Avoid or strictly limit infant positioning devices, as this equipment puts added pressure on baby’s head while also limiting his mobility. Positioning devices include, but are not limited to, devices such as swings, bouncy seats, lounger pillows, and car seats used outside of the car. As baby’s mobility improves, she is changing the forces on her skull. It is important for your baby to learn how to turn her head fully to both sides, roll from side to side and between her back and tummy, and eventually to sit so that there is no longer pressure in one spot on the back of their head. Developing these skills will not only help your baby to decrease the asymmetrical pressure on his head and improve head shape, but will also give him a strong foundation for future movement and motor skills. Remember that infants often benefit from physical therapy to help them improve their symmetry of movement if they have a tendency to turn their head in one direction. If you have concerns about your baby’s head shape, think about giving her more opportunities for uncontained play, encourage tummy time as much as possible, and most importantly, speak with your pediatrician.