Construction of growth reference values in children aged 0-18 years in Turkey

Population based growth studies reveal development and welfare levels of societies, while monitoring growth at individual level is important in order to follow processes such as acute and chronic malnutrition, diseases, genetic disorders, growth spurt and growth failure. On the other hand, reveal of the secular trends observed in growth at routine intervals provides the healthiest monitoring of the changes occurring in welfare levels of societies. This entails regular monitoring growth of each child from the time of birth, which in turn makes creating population specific growth reference curves inevitable. Absence of updated growth references obtained countrywide from children aged 0-18 years in Turkey is an important lack. In this study, we aimed to reveal growth status of healthy children aged 0-18 years who live under good conditions in Turkey, and to create reference growth values. In this context, a total of 6556 babies and children with 3295 being boys and 3261 girls living in the provinces of Istanbul, Ankara, Izmir, Adana, Samsun, Diyarbakir, and Erzurum were examined, and the first multicenter growth reference values were construct so as to involve 0-18 age range in Turkey. Of the study population, babies in 0-1 year age group were examined with 3-month periods, babies in 1-2 years age group with 6-month periods, and children in 3-18 years age group with yearly periods. Ages of the persons in the sample were calculated by the decimal system. The measurements of weight, height, and head circumference that are the most important anthropometric variables were read according to the techniques recommended by International Biological Programme. In order to determine the level of fatness (obesity), relative scale was used in babies aged 0-3 years, while body mass index (BMI) values were calculated in children aged 3-18 years. Measurements were taken from babies and children who were brought for control to the Health Children Outpatient Clinics of the university hospitals in persons aged 0-3 years, and from children who had education in primary, middle, and high schools in persons aged 3-18 years. Besides basic statistical results of the variables such as mean and standard deviation, distribution statistics (kurtosis and skewness) were calculated using SPSS (Statistical Package for the Social Sciences) software. LMS method was used to create percentage curves and to smooth the curves. In addition, 3-month growth rate charts were created for 0-3 years age group, and yearly growth rate charts for 3-18 years age group. According to the results of this study which is the first in Turkey for involving countrywide and being performed as a multicenter study; the mean height and weight of the babies and children included in the current study were somewhat higher compared to their peers involved in references by the WHO 2006 and Neyzi 2008, from the first months up to 3 years of age. The mean height of the girls aged 3-5 years was very close to the curves in the WHO 2007 and Neyzi 2008, and from the relevant age, girls in our study grew more rapidly compared to their other peers. Whereas boys aged 4-16 years were over their peers living both in Istanbul and the USA in terms of weight and height. BMI curves indicated that the mean weight of the persons in our sample was higher than their peers living both in Istanbul and the USA until 17-18 age of years. According to the head circumference reference curves; the mean head circumference was slightly larger in children living in our country than their American peers. On the other hand, given the previous reference studies, it can be said that a significant positive secular change occurred in term of height. In conclusion according to this study which was performed in seven different regions, growth level of the babies and children living under relatively good conditions in our country reached to the standard values, and even sometimes they have a growth potential higher than these standards. Keywords: Growth and development, growth references, anthropometry, LMS method, secular trend