Do flat heads last into adulthood? What adult head scans and 2,800-year-old skulls show

It depends on the study, but it isn't rare. In 2026, doctors in Japan measured head scans from 242 people aged 15 to 39 who'd had a CT scan in an emergency department, with nothing wrong inside the head.¹ More than half (53%) met the criteria for plagiocephaly, a flat spot on one side, and nearly 1 in 5 (19%) had moderate to severe flattening. People born before and after Japan's back-to-sleep campaign had similar head shapes, and men's heads measured more uneven than women's.¹

A German study published the same year found far fewer. Researchers used 3D photos to measure the heads of 146 teenagers and adults, average age 26, most of them patients at a hospital jaw clinic. About 1 in 9 (11.5%) had more asymmetry than the cut-off used for babies on one common measure, and 7% on another.² The authors took this to mean flat spots are less common in adulthood than in infancy.

Why the gap? Different countries, different groups of people, different ways of measuring and different cut-offs. Neither study has baby records, so nobody knows how these heads looked at 4 months. What both show is that uneven head shapes are still measurable in some groups of adults.

That flat heads aren't new, and that they can last into adulthood. In 2026, researchers in Italy examined 26 adult skulls from Matelica, in central Italy, dating from about 800 BC.³ 11 of the 26 (42%) were flat at the back on one side. Most were on the right (73%) and most were male (64%). 7 people had signs in their skeletons possibly consistent with a tight neck (congenital muscular torticollis).³

That's the same pattern doctors see in babies today: more often on the right, more often in boys, and often with a tight neck.⁴ The researchers think it came from babies spending long stretches with their head in one position, possibly because of how they were cared for.³ These were adults, so the flattening was still visible long after infancy.

Because a flat area changes most while the head is growing fastest, and that's in the first months.⁵ Once your baby can move their head freely, usually by about 4 months, the flattening stops getting worse, but nothing pushes the flat area back out. The head grows around it.⁶ Does a baby's flat head go away on its own? goes through it month by month.

A flat spot that lasts is about how the head looks. A positional flat head doesn't affect brain development.⁷ Does a flat head affect my baby's development? covers the research in full.

Act early rather than wait and see. None of this means you did anything wrong, and back sleeping is still the right advice for every baby.⁸

The Perfect Noggin is a contoured head shaping surface designed by paediatric craniofacial surgeon Dr Gary Rogers. Its recessed cup takes the pressure off the flat area, so growth can go back into it while the head is growing fastest. Your physio works on the neck. Once your baby starts rolling from back to tummy, use it supervised only (watching on a video monitor counts), and stop once they're rolling regularly.