OBJECTIVE: This study was designed to statistically evaluate the independent and interacting effects of biological and environmental risk factors that influence lateralization of deformational plagiocephaly (DP) in an attempt to provide future guidance for clinical treatment.
METHODS: A database of >20000 children treated for DP was examined by using 2- and 3-way factor analyses for categorical frequency data, representing the largest statistical analysis of DP to date. Data on parity, zygosity, intrauterine presentation, birth number and weight, sleep position, lateralization, and sex were collected from parents of children with DP who were treated at Cranial Technologies, Inc, from 1990 to 2007.
RESULTS: As with most DP studies, male patients were significantly overrepresented. Nonetheless, after statistically accounting for sex in our analyses, DP is significantly correlated with primiparity, fewer vertex but more breech and transverse intrauterine presentations, twinning (specifically, dizygosity), and, finally, right-sided lateralization. Additional analyses revealed that several factors correlated with DP, such as intrauterine presentation, sleep position, and lateralization, are not easily explained by an underlying biological factor. Instead, sleep position was the single greatest predictor of lateralization.
CONCLUSION: Although previous studies have argued for both environmental and underlying biological factors associated with DP, we found that lateralization in children with DP could be largely explained by environmental factors such as sleep position.