Prevalence and predictors of idiopathic asymmetry in infants born preterm.

An idiopathic asymmetry in posture of the head is recognized as a risk factor to develop a deformational plagiocephaly (DP). In our neonatal follow-up clinic, an IA is often observed in infants born preterm at term-equivalent age (TEA).To explore (1) the prevalence of an idiopathic asymmetry in 192 infants (gestational age ≤32.0 weeks) at TEA and 6 months corrected age (CA), (2) whether demographical, perinatal, and medical factors were predictors of the asymmetry, and (3) differences in motor maturation between infants with and without asymmetry.In a retrospective study, frequencies of idiopathic asymmetry and DP, putative predictors, and Alberta Infant Motor Scale scores at 6 months CA were abstracted and analyzed with Chi(2), Mann-Whitney, logistic regression and T-test.The prevalence rate of a positional preference of the head at TEA was 44.8% (n=86), 10.4% (20/192) had a DP at TEA and 13% (25/192) at 6 months CA. Positional preference, multiple birth and male gender predicted the presence of DP (p<.05, odds ratio 3.0, 3.2, and 3.1 respectively). Gross motor maturity at 6 months CA was less developed in infants with a positional preference at TEA compared to preterm norms (p=0.01).The high prevalence of a positional preference in infants born preterm at term equivalent age requires extra alertness to prevent the development of a deformational plagiocephaly, especially in boys and twins. Although, considering the lower prevalence of plagiocephaly at 6 months CA, therapists should be aware of over treating these infants.