Association Between Body Mass Index and Blood Pressure Among Urban and Rural School-Going Children in Chennai District: A Comparative Cross-Sectional Study

Abstract

Background: Childhood obesity and hypertension are growing public health concerns, with evidence suggesting that elevated blood pressure in children is strongly associated with increased body mass index (BMI). However, urban–rural differences in this association have not been extensively studied in South Indian schoolchildren.

Objectives: To determine the prevalence of overweight, obesity, and hypertension among school-going children in urban and rural areas of Chennai district, and to assess the association between BMI and blood pressure.

Methods: This cross-sectional study included 660 school children aged 6–16 years, with 330 each from urban and rural schools, selected using stratified random sampling. Anthropometric measurements were recorded using standardized techniques, and BMI was classified according to NCHS percentiles. Blood pressure was measured thrice at 10-minute intervals in the right arm, and mean values were classified as normal, pre-hypertensive, or hypertensive based on age-, sex-, and height-specific percentiles. Data were analyzed using SPSS v21, with descriptive statistics, unpaired t-tests, and Pearson’s correlation.

Results: The prevalence of overweight and obesity was 12.1% and 4.5% in urban children, compared to 6.4% and 2.1% in rural children (p<0.01). Hypertension was observed in 6.7% of urban children and 3.3% of rural children (p=0.04). BMI showed a significant positive correlation with both systolic blood pressure (r=0.42, p<0.001) and diastolic blood pressure (r=0.35, p<0.001). Overweight and obese children had a 3.8-fold higher risk of hypertension compared to children with normal BMI.

Conclusion: Urban school children in Chennai district have a higher prevalence of overweight, obesity, and hypertension compared to rural counterparts. BMI is strongly associated with blood pressure, highlighting the need for early screening and lifestyle interventions in school health programs.