Pattern of sex differences in growth of Saudi children and adolescents.

BACKGROUND Although variations in growth between boys and girls have been reported, detailed descriptions according to age and growth parameters are not available. OBJECTIVE The goal of this study was to determine the pattern and magnitude of differences in growth between boys and girls according to age that justify separate growth charts. METHODS The data set was based on a cross-sectional representative sample of the Saudi population of healthy children and adolescents from birth to 19 years of age. Body measurements (length, height, weight, and head circumference) were performed according to standard recommendations; body mass index was also determined for each subject. The difference in growth between boys and girls was assessed based on z scores and percentiles (5th, 50th, and 95th) of growth parameters using 2 age groups (0-3 years and 2-19 years). The significance of the difference between boys and girls for any growth parameter was tested by ANCOVA. RESULTS A total of 35,279 children and adolescents from birth to 19 years of age satisfied the criteria for growth measurements. There were 17,880 boys and 17,399 girls; all were Saudi nationals. The Saudi boys were generally taller and heavier than girls up to approximately 7 to 10 years of age. Thereafter, girls generally were taller and heavier than boys from 10 to 14-15 years of age. After that, boys again were taller and heavier. Similar variations were observed for body mass index and head circumference. The difference between boys and girls for each growth parameter was highly significant (P < 0.001). CONCLUSIONS Based on analysis of these Saudi children and adolescents, the difference in growth between boys and girls was not uniform but depended on age. However, the pattern was remarkably consistent across all growth parameters and appears to reflect the timing of maturation between boys and girls.