Auricular anthropometry of newborns at the Singapore General Hospital

Abstract

Introduction: External ear abnormalities accompany many syndromes and genetic conditions. Yet, there are currently limited Asian references and no local norms for ear measurements and definitions for "low-set ears". The authors therefore describe ear measurements in a Singapore newborn population and seek to establish the applicability of the general accepted definition of "low-set ears" being that of "less than a third of the entire ear height being above the inter-medial canthal line". Materials and Methods: Babies managed by the Department of Neonatal and Developmental Medicine during a 3-week period were measured by 2 investigators using the Feingold and Bossert technique. Intra- and inter-rater reliabilities were calculated. The influence of various anthropometric factors on and their relationships with ear length (EL) and width (EW) was analysed. Results: A total of 104 neonates (20% preterm at birth) were included in this study. Median gestation was 38 weeks (range, 32 to 42). Mean birth weight was 2910 ± 657 g. Mean EW and EL for term infants were 2.1 ± 0.1 cm and 3.6 ±s 0.3 cm respectively, without significant differences for different-sided ears, investigators, race or gender. Mean percentage of right and left ear above the denoted line was 52 ± 9% and 47 ± 10% respectively (P = 0.000), with 3rd percentile being 33%. Conclusions: Singaporean neonatal ears are comparable with other Asian neonates - larger than Hong Kong Chinese babies, though similar to Japanese newborns - but smaller than Caucasian neonates. The definition of "low-set ears" is consistent with the general accepted definition.