The course of positional cranial deformation from 3 to 12 months of age and associated risk factors: a follow-up with 3D imaging.

Deformational plagiocephaly is reported in up to 46.6 % of healthy infants, with the highest point prevalence at around 3 months of age. Few prospective studies on the natural course of skull deformation have been conducted, and we know of no studies using 3D imaging starting from the highest point prevalence period. In this prospective, population-based cohort study, we describe the course of cranial asymmetry and shape in an unselected population using 3D stereophotogrammetry and investigate factors associated with late cranial deformation and failure to recover from previous deformation. We evaluated 99 infants at 3, 6, and 12 months of age. We acquired 3D craniofacial images and performed structured clinical examinations and parental interviews at each visit. Eight outcome variables, representing different aspects of cranial shape, were calculated from a total of 288 3D images. Scores of asymmetry-related variables improved throughout the observation period. However, the rate of correction for cranial asymmetry decreased as the infants grew older, also in relation to the rate of head growth, and a significant amount of asymmetry was still present at 12 months. Positional preference at 3 months predicted an unfavorable course of cranial asymmetry after 3 months, increasing the risk for DP persisting. What is known: • The prevalence of deformational plagiocephaly spontaneously decreases after the first months of life. • Limited neck range of motion and infant positional preference increase the risk of deformational plagiocephaly during the first months of life. What is new: • Positional preference at 3 months predicts an unfavorable spontaneous course of deformation also from three to 12 months of age, presenting a potential target for screening and treatment. • The spontaneous rate of correction for cranial asymmetry decreases after 6 months of age, also in relation to the rate of head growth.