OBJECTIVETo study the Kaup index (KI), an index used to evaluate body burliness and nutritional status, of neonates with a gestational age (GA) of 27-42 weeks at birth, and to establish the percentile curves of KI.

METHODSCross-sectional cluster sampling was performed from April 2013 to September 2015 to select 16 887 singleton neonates with a GA of 27-42 weeks in two hospitals in Shenzhen, China. Body weight and body length were measured to calculate KI. The percentile curves of KI were plotted in these neonates.

RESULTSMean KIs and corresponding standard deviations were obtained for singleton neonates with a gestational age of 27-42 weeks (in male, female, and mixed groups), and the 3rd-97th percentile curves of KI were plotted. The singleton neonates with a GA of 27 weeks had the lowest 50th percentile value of KI, and KI gradually increased with GA. Boys had a higher 50th percentile value of KI than girls in each GA group. In all groups except the 33-week GA group, boys had a higher mean KI than girls, and there was a significant difference in the mean KI between boys and girls in the GA groups of 34 and 36-40 weeks (P<0.05).

CONCLUSIONSKI of neonates at birth increases with GA, suggesting that body density and body burliness increase with GA. Boys have better body burliness than girls at birth. The percentile curves of KI plotted for singleton neonates with a GA of 27-42 weeks (in male, female, and mixed groups) can provide a reference for evaluating the body burliness and nutritional status of neonates at birth in Shenzhen.