Background: Normal standard references of blood pressure (BP) for children and adolescents have been suggested to be constructed based on anthropometric indices. Accordingly, we aimed to develop first BP reference percentiles by weight and age for Iranian children aged 3-18 years old. Materials and Methods: A total of 16,246 children and adolescents aged 3-18 years were included from 3 cross-sectional studies conducted in Tehran- Iran. Data on demographic characteristics, anthropometric indices and BP values of these subjects were gathered. Quantile regression model was used to assess the need for weight adjustment in different percentiles of systolic and diastolic BPs with age, gender, and the corresponding weight percentiles. Then, Age- and sex-specific BP nomograms were developed according to weight. Results: All the regression coefficients for weight percentiles were statistically significant in quantile regression of BPs, which confirms the positive effect of adjustment for weight (P < 0.05). The BP percentiles by age and weight are presented for each gender. All the BP percentiles rose steadily in all the weight percentiles with minor discrepancies between the two genders. Based on the weight-adjusted BP curves, lean subjects are estimated to have a higher prevalence of hypertension while this figure is lower among the overweight and obese children. Conclusion: This study presents the first Iranian BP references by age and weight for 3 to 18 year old children and adolescents. BMI-adjusted BP curves were found to be a better tool for assessing the prevalence of hypertension in children and adolescents, on the basis of which a more reliable classification standard for hypertension could be obtained
