Auricular anthropometry of newborns at the Singapore General Hospital

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".

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.

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 +/- 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%.

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.