The relationship of body mass index and blood pressure in Iranian children <7 years old.

The objective of this study was to evaluate the association between the body mass index (BMI), in healthy young children with their blood pressure (BP). The study included 3186 healthy children aged 1-6 years who were studied between March 2004 and March 2007 in different kindergartens and health centers in Tehran. Each child was classified on the basis of age- and sex-specific BMI percentile as normal weight (BMI <85th percentile), at risk for overweight (BMI >85th and <95th percentile), or overweight (BMI > or =95th percentile). Systolic BP (SBP) and diastolic BP (DBP) was compared among age-sex-BMI groups. Among children aged below 7 years in kindergartens and health centers in Tehran, 7.2% were at risk of overweight and 12.2% were overweight. These proportions were similar for boys and girls and were as follows: 6.9%, 13.9% and 7.5%, 10.5%, respectively. Analysis of variance showed that mean SBP significantly increased according to age (p < 0.0001) and BMI group (p = 0.001). Analysis of variance also showed that mean DBP significantly increased as age increased (p < 0.0001), but no significant difference was found between boys and girls in different age and BMI groups (p = 0.37). Our survey identified a high prevalence of overweight that was associated with elevated SBP among preschool-aged children in Iran. The effect of higher BMI on mean SBP is present in childhood and can be used as a predictor of high SBP even in children as young as 1-6 years.