Plagiocephaly (flat head) in babies

What does the evidence show for plagiocephaly in babies?

• Deformational (positional) plagiocephaly affects an estimated 15% to 20% of infants, with some reports as high as 46.6%, a 400% to 600% increase compared with rates before 1992, tracking closely with the rise of back-sleeping safe-sleep guidance. 1
• Risk factors for the deformational type include abnormal positioning before birth, a forceps- or vacuum-assisted delivery, prematurity, multiple gestation (twins or more), male sex, a larger head circumference, supine sleeping, limited neck rotation, congenital muscular torticollis, and insufficient tummy time or overall activity. 1
• Deformational plagiocephaly typically becomes noticeable weeks after birth and is usually identified before 4 months of age, producing a parallelogram-shaped head from above with flattening on the opposite side from where the forehead bulges. This is distinct from craniosynostosis, a fused-suture condition present at birth that produces a trapezoid shape, flattening and bulging on the same side, and a firm ridge along the fused suture on exam. 1
• First-line, conservative management includes changing sleep posture within safe-sleep guidelines, counterpositioning, using toys to encourage the baby to turn their head both directions, and supervised tummy time during awake periods. 1
• In infants with congenital muscular torticollis, plagiocephaly was present in 40.7% of cases, and restricted mobility of the cervical spine is considered one of the main predisposing factors for positional plagiocephaly, in infants averaging around 4 months of age in that research. 2
• A 2026 systematic review found helmet therapy speeds up early correction of cranial asymmetry, particularly in moderate-to-severe cases, but current evidence does not show clear long-term superiority over conservative repositioning management, and starting any intervention before 5 to 6 months of age is linked to greater improvement regardless of which approach is used. 3
• The same review recommends a stepwise, severity-based approach: conservative management first for mild deformities and early presentation, escalating to helmet therapy for moderate-to-severe cases, limited response to repositioning, or later presentation, with the decision individualized to severity, age, response so far, and family preference. 3
• Because head shape is largely established within the first few months of life and can persist long-term if unaddressed, routine pediatrician visits in the first 6 months are an important window for catching this early, and the World Health Organization recommends supervised tummy time both for gross motor development and because it can reduce how often positional plagiocephaly occurs. 4

Conservative management vs. helmet therapy

When should I call my provider about plagiocephaly in babies?

Positional plagiocephaly usually shows up as a parallelogram-shaped flattening seen from above, developing gradually over the weeks after birth rather than being present at birth, and it generally improves with repositioning. A different pattern deserves a prompt evaluation rather than a wait-and-see approach at home: a head shape that was already noticeable at birth, a trapezoid shape from above, a firm ridge you can feel along one of the skull's suture lines, or flattening that keeps worsening despite consistent repositioning and tummy time. These can point to craniosynostosis, a fused skull suture that needs a specialist's assessment rather than a repositioning approach, so raise any of these specifically with your pediatrician. When in doubt, call your obstetric team the same day. Early input almost always beats waiting, and the on-call line exists exactly for this.