Non-obstetric risk factors for deformational plagiocephaly: A systematic review and meta-analysis

Plagiocephaly is defined as asymmetrical distortion of the skull resulting in an oblique trapezoid or parallelogram head shape. In the absence of skull growth restriction due to craniosynostosis, deformational plagiocephaly (DP) is caused by deformational forces acting on one side of the back of the head which distorts the normal symmetry of the skull. The aims of this systematic review and meta-analysis were to critically assess the evidence for non-obstetric risk factors for DP and to make evidence-based recommendations for reducing the prevalence of DP. A search of PubMed and Web of Science was performed covering 21 August 2010 to 21 August 2022. The searches yielded 159 articles, of which 18 articles were eligible for inclusion in this study. 43 non-obstetric factors were identified. Of these, a total of 17 factors were associated with DP. With the notable exceptions of maternal age, mechanical ventilation and tummy time, these associations were either supported by non-conflicting evidence or a meta-analysis that resolved conflicting evidence into a significant association. Thirteen factors had significant odds ratios that ranged from 1.10 (mechanical ventilation) to 7.15 (insufficient vitamin D intake). Of the five factors assessed by meta-analysis (male gender, reaching fewer motor milestones by six months of age, maternal education level, head position preference, sleeping position), only one (male gender) was associated with significant inter-study heterogeneity. No evidence of publication bias was detected. In summary, this study provides the most comprehensive meta-analytic assessment of non-obstetric factors associated with DP published to date. It provides 13 evidence-based recommendations which can be adopted by healthcare systems globally, to reduce the prevalence of DP and its impact on child development.