Neonatal morphometric indices of fetal growth: analysis of observer variability

Measurements of triceps and subscapular skinfold thickness, mid-arm circumference (MAC), head circumference (HC) and crown-heel length were performed by two observers in 30 healthy neonates. Intra-observer standard deviation for all measurements, calculated using one-way analysis of variance, was small and similar for each observer. Inter-observer variability was assessed using limits of agreement. There were small, systematic, differences between observers for measurements of triceps skinfold thickness and crown-heel length, and for calculated ponderal index (PI). When related to respective published reference ranges, the 95% prediction intervals for subscapular (-0.51, 0.68 mm) and triceps (-0.65, 0.29 mm) skinfold thicknesses were less than those for the MAC/HC ratio (-2.1, 1.9) and PI (-0.23, 0.28). The results indicate that skinfold thickness measurements are a more robust measure and, therefore, may be of greater value in the assessment of neonates with suspected fetal growth retardation.