Are the World Health Organization growth standards universal? The Israeli children validity study

Aim: The World Health Organization (WHO) 2006 growth standards were adopted in most countries, Israel included. We aimed to study the assumption that growth in early years is similar across populations by studying the validity of the WHO growth standards in a large population-based study of Israeli infants. Methods: Computerized data on infants born in 2011–2015 who were followed in the well-baby clinics for the first 2 years of their lives were retrieved from the Ministry of Health. Data included sociodemographics, delivery information, and visit-specific measurements of weight, recumbent length, and head circumference. Sex- and age-specific z-scores, percentiles, and outliers of anthropometric measurements were calculated and compared with the Standards. These analyses were repeated for “ideally grown” infants. Results: Israeli infants were consistently shorter, with z-scores ranging from −0.07 SD (standard deviation) to −0.5 SD. Also, Israeli infants weighed less than predicted by the standards in the first 9 months. The proportion over 2 SD in weight-for-length increased with age from 2.2–2.9% in the first 6 months of life to 3.4–5.1% in the second year of life, which is well above the expected value of 2.3%. Conclusion: Israeli infants were shorter and more likely to be obese than predicted by the Standards. Having differences in length even more prominent among “ideally grown” children suggest that the WHO standards might not be optimal for monitoring the growth of Israeli infants.