How do the standards relate to the WHO standards that we know so well? The WHO-initiated Multicentre Growth Reference Study (MGRS), which was launched in 2006, published growth standards for infants and children under five years of age and is now used in more than 125 countries worldwide. The significance of the WHO growth standards is twofold: 1) the multicentre study was conducted in six countries: Brazil, Ghana, India, Norway, Oman, and the United States; and 2) the sample was exclusively breastfed infants whose mothers were non-smokers and minimally affected by environmental factors that limit growth and development. There are universal patterns of growth and developmental change. When growth conditions are optimal and the population is carefully selected and healthy, the values of weight and growth rate of infants are very similar across countries. The authors of this study conducted a systematic review of various standards of neonatal physical measurements and found that there are 104 different standards of neonatal physical measurements of varying quality worldwide. The use of different standards makes it difficult to assess the nutritional status of newborns, especially the prevalence and mortality of small-for-gestational-age (SGA) infants, and makes cross-population comparisons difficult. Therefore, there is a need to construct an international standard for neonatal physical development. The main findings of this study Birth weight is influenced by many factors, including gestational age, maternal birth weight, maternal age, maternal BMI, maternal diet during pregnancy, and the presence of diseases such as malaria. Maternal weight gain during pregnancy was only significantly associated with the birth weight of female infants, while paternal birth weight was only significantly associated with the birth weight of male infants. Therefore, the quest to define the ideal birth weight is a complex project. The INTERGROWTH-21st project followed the methodology of the WHO Multicenter Growth Reference Standards Study over 4 years, with a study sample of more than 20,000 newborns from 8 regions who met inclusion and exclusion criteria. The trained study team measured the weight, length and head circumference of newborns at 12 hours of life. Most of the data were based on repeated measurements, and the values of the measured variables were extremely close across the eight countries. The 50th (P3-P97) percentile measurements for male infants at 40 weeks of gestational age were as follows: birth weight 3.38 kg (2.63-4.22); length 49.92 cm (46.75-53.13); and head circumference 34.31 cm (32.15-36.56). -36.56). Measurements for female infants were: birth weight 3.26 kg (2.55-4.08); body length 49.23 cm (46.12-52.22); head circumference 33.76 cm (31.72-35.92).