In Korea, when a baby sleeps soundly, whether lying flat or with their head turned to one side, parents don’t just admire the peaceful sight. They have a task at hand: gently repositioning the baby’s head from side to side during sleep. It’s a small but deliberate effort to prevent flat head syndrome and encourage a well-rounded head shape.

While flat head syndrome is a real condition caused by constant pressure on the back or side of a baby's head, South Korean parents often have additional concerns. They believe the shape of the head forms the foundation of the face and that a flat head can interfere with the development of the baby's facial features.

Since a baby’s skull is still soft and developing, many Korean parents see infancy as a crucial window to shape a round, gently protruding back of the head, commonly called "jjanggu head," believing it will lead to a smaller, more sculpted face later in life.

“Jjanggu,” although best known as the Korean name for the popular Japanese animated character Shin-chan, is also a Korean word defined in dictionaries as a head shape characterized by a prominent forehead or occipital area.

To prevent flat head, many parents make a habit of regularly alternating their baby’s sleeping position from one side to the other. Some position their newborns to sleep on their sides or even on their stomachs, to avoid putting pressure on the back of the baby’s head. There are even side-sleeping pillows on the market designed for newborns to lie on their side and wrap their little arms around the cushion.

But many pediatricians in Korea and other countries strongly warn against putting babies to sleep on their stomachs or sides, as it has been directly linked to Sudden Infant Death Syndrome.

There have been numerous cases of infants dying while sleeping face-down. Just last year, a baby at a daycare center in Daegu died during a nap after being placed in a prone position following lunch.

Some parents, unwilling to choose between safety and aesthetics, turn to head-shaping pillows featuring a dip in the middle. They are advertised as softly cradling the baby’s head and preventing flattening.

However, a local pediatrician surnamed Song says that those pillows are a product of Korea’s beauty-obsessed parenting culture, calling them a form of "misleading marketing."

"In most cases, a baby’s head shape naturally corrects itself with growth. Sleeping face-down can block a baby’s airway or interfere with body temperature regulation, so it requires special caution," he said.

Next time you see a “jjanggu” pillow online while shopping for a baby shower gift in Korea, remember that it’s not about the anime character but about "K-beauty" starting in infancy.