The case for more tummy time

In 1992, the American Academy of Pediatrics introduced the"back to sleep” campaign. Before then, Americans traditionally put their babies to sleep on their tummies, but that position was discovered to be associated with every new parent’s worst nightmare, crib death. Since the start of the campaign, parents have been encouraged to put their baby to sleep face up and with that simple change in position sudden infant death syndrome (SIDS) deaths are down by 40 percent. That’s success!

But as a result, there has been a dramatic rise in a couple of issues parents should be aware of. First, sleeping on their back can leave many babies with a slightly flattened head, and second, babies who spend a lot of time on their back have slightly slower motor development. Neither of these are deadly or even harmful in the long term, but they can cause concern for parents so they’re worth addressing.

Babies are born with soft spots in their skulls to allow for the rapid brain growth that occurs in the first year of life. This also makes their heads very moldable and easily misshapen. Infants sleep on their backs for many hours every day and for some babies their head tends to always fall to the same side. Over time the skull can become flattened on that side causing a condition known as positional plagiocephaly (play-gee-oh-ce-pha-lee). Today, because of the change in sleeping position from tummy to back, plagiocephaly occurs in as many as one out of every three babies, which is way up from one out of 300 babies many years ago.

Positional plagiocephaly is easily visible to a casual observer. It is not life-threatening and doesn’t affect brain development, but it can lead to improper skull growth and permanently affect the symmetry of a child’s face if it isn’t treated properly. That’s why if parents notice this flattening, they should bring it to the attention of their pediatrician.

Most cases can be treated by alternating the position of the baby’s head each night. In other words, turn it to the left side one night, the right side the next. This should be done at nap times as well. You may have to put the baby in the crib with their head facing in an opposite direction every other night so they naturally want to look toward the door or in the direction of household sounds. Sometimes babies keep their head turned to one side because of a condition called torticollis, which is due to tightening of the neck muscles. This condition can be treated with simple stretching exercises at each diaper change. The pediatrician or a physical therapist can provide these exercises.

If the baby’s head does not reshape with repositioning, your doctor may recommend referral to a pediatric neurosurgeon for a molding helmet. The helmet has a hard plastic exterior and foam interior and is generally worn 23 hours per day. It guides the baby’s head growth to allow the flat part of the skull to expand and round out.

In general, plagiocephaly is best treated in the first year of life since as the baby gets older the bones become less pliable and head growth slows, making correcting the shape more difficult.

The success of the"back to sleep” campaign has also unexpectedly led to slightly slower motor development in children.

Tummy time is critical for infants to develop their neck, shoulder and back muscles, which are all essential for sitting, crawling and walking. When babies used to sleep on their tummies, this happened naturally. Now parents should make an effort to put their baby on their belly several times a day while awake. That position can feel uncomfortable for some babies, so they can start practicing this position on the parent’s chest, tummy or lap. As the baby gets older floor play should be encouraged on a blanket or mat where the baby can practice head lifting, reaching and pivoting skills. If the baby really hates tummy time, parents can go head to head with their baby on the floor or get a mirror or toys to capture the baby’s attention.

It’s true that babies who sleep on their back will lag slightly behind their peers who sleep on their tummies, but parents shouldn’t worry too much about that. Babies are pretty amazing and their motor development will catch up by 18 months of age.

The"back to sleep” campaign has been a huge success. It has saved many babies’ lives and has given parents peace of mind. Positional plagiocephaly and slightly slower motor development are the small price for this improved care.

Dr. Lisa Thornton, a mother of three, is director of pediatric rehabilitation at Schwab Rehabilitation Hospital and LaRabida Children’s Hospital. She also is assistant professor of pediatrics at the University of Chicago. E-mail her at

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