Deformational plagiocephaly

A common condition with uncertain causes

Deformational plagiocephaly refers to flattening or asymmetry of an infant’s skull without premature fusion of the cranial sutures. It is common in otherwise healthy babies, but the relative contribution of positioning, movement, prenatal factors and other influences has been debated.

In 2017, Freia De Bock, Verena Braun and Herbert Renz-Polster published a systematic review of proposed causes and hypotheses. The review found that the available evidence was heterogeneous and that simple explanations did not fully account for the condition.

The evolutionary mismatch hypothesis

The 2018 paper approaches the problem through evolutionary medicine. If supine sleep is safest for young infants, why should that position itself routinely produce a socially salient head deformation?

The paper proposes that sleeping on the back may not be sufficient on its own. The mismatch may lie between supine sleep and aspects of modern infant care that reduce variation in head position and movement — including long periods on firm, flat surfaces.

This is explicitly a hypothesis intended to clarify questions for research. It does not overturn the evidence that placing infants on their backs to sleep reduces SIDS risk.

Clinical context

Skull asymmetry has several possible causes, and craniosynostosis requires different assessment and care. This page is not a diagnostic guide. Concerns about an infant’s head shape or movement should be discussed with a pediatric clinician.