A television commercial aired a number of years ago, in which a toddler, upon seeing a newborn baby, says to the young mother, “Too bad you had to get a bald-headed one.”

If a similar commercial aired today, the toddler would likely say, “Too bad you had to get a flat-headed one.”

In 1992, the National Institute of Child Health and Human Development, Maternal and Child Health Bureau, American Academy of Pediatrics, SIDS Alliance, and The Association of SIDS and Infant Mortality Programs launched the “Back to Sleep” campaign in an effort to reduce the risk of Sudden Infant Death Syndrome (SIDS)—the leading cause of death in children between 1 month and 1 year of age.

Since the campaign launch, the incidence of SIDS has declined by nearly 50 percent, while the incidence of plagiocephaly, flat head syndrome, has greatly increased. Flat heads are a small price to pay for preventing SIDS, given that plagiocephaly can often be prevented or easily corrected. But perhaps if more parents knew the cause of flat heads, they could take actions to prevent it.

Exactly how do babies get flat heads?
When babies are born, their heads are made up of soft bones that slowly fuse together over time. The bones are soft, so the baby’s brain has room to grow. When babies spend a lot of time in one position, for example, on their back, a flat spot can form on their heads, and little or no hair may grow on that spot. So your bundle of joy could actually be a bald-headed one and a flat-headed one.

Can flat heads be prevented?
To keep your baby from getting a flat head, place him face down on his tummy (stomach) when he is awake or carry him upright in an infant carrier or sling. Tummy time also helps to strengthen the muscles needed for crawling and sitting. Because the risk of SIDS is greater when babies are on their tummies, don’t leave your baby alone during tummy time. If you need to leave your baby alone, even for a minute or two, place him on his back. You can put him back on his tummy when you return.

Preterm babies (babies born early) are more likely to get flat spots on their heads because their heads are even softer than full-term babies’ are. Also, preterm babies often spend more time on their backs without being moved or held. To prevent flat heads, parents of preterm babies are encouraged to hold their babies skin-to-skin against their chest. This is called kangaroo care. Kangaroo care can also help to regulate a baby’s body temperature, heart rate, and breathing rate.

The best way to keep you baby safe is to always put your baby on his back to sleep (not on his side and not on his tummy). But when those eyes are open, it’s bottoms up!