Measurement of body composition is increasingly important in research and clinical settings but is difficult in very young children. Bioelectrical impedance analysis (BIA) and air displacement plethysmography (ADP) are well-established but require specialist equipment so are not always feasible. Our aim was to determine if anthropometry and skinfold thickness measurements can be used as a substitute for BIA or ADP for assessing body composition in very young New Zealand children. We used three multi-ethnic cohorts: 217 children at a mean age of 24·2 months with skinfold and BIA measurements; seventy-nine infants at a mean age of 20·9 weeks and seventy-three infants at a mean age of 16·2 weeks, both with skinfold and ADP measurements. We used Bland–Altman plots to compare fat and fat-free mass calculated using all potentially relevant equations with measurements using BIA or ADP. We also calculated the proportion of children in the same tertile for measured fat or fat-free mass and tertiles (i) calculated using each equation, (ii) each absolute skinfold, and (iii) sum of skinfold thicknesses. We found that even for the best equation for each cohort, the 95 % limits of agreement with standard measures were wide (25–200 % of the mean) and the proportion of children whose standard measures fell in the same tertile as the skinfold estimates was ≤69 %. We conclude that none of the available published skinfold thickness equations provides good prediction of body composition in multi-ethnic cohorts of very young New Zealand children with different birth history and growth patterns.

在研究和临床环境中，身体成分的测量越来越重要，但对于年幼的儿童却很难。生物电阻抗分析（BIA）和空气体积体积描记法（ADP）已建立完善，但需要专业设备，因此并不总是可行的。我们的目标是确定人体测量学和皮褶厚度测量是否可以替代BIA或ADP来评估新西兰年幼儿童的身体成分。我们使用了三个多族裔队列：217名平均年龄为24·2个月的儿童，进行了皮褶和BIA测量；平均年龄为20·9周的79例婴儿和平均16·2周的73例婴儿，均进行了皮褶和ADP测量。我们使用Bland–Altman图将使用所有潜在相关方程式计算的脂肪和无脂肪质量与使用BIA或ADP进行的测量进行比较。我们还针对测量的脂肪或无脂肪质量和三分位数计算了同一三分位数中的儿童比例（i）使用每个方程式计算；（ii）每个绝对皮褶；以及（iii）皮褶厚度的总和。我们发现，即使对于每个队列的最佳方程，与标准量度一致的95％的限制也很广（平均值的25–200％），并且标准量度与皮褶估计值处于同一三分位数的儿童比例为≤69％。我们得出的结论是，没有可用的已公布皮肤皱纹厚度方程式能够很好地预测具有不同出生史和生长方式的非常年轻的新西兰儿童的多种族队列。