Relation between birthweight and blood pressure among 7-8 year old rural children in India

Background Fetal malnutrition has been proposed as a cause of higher blood pressure. However, some studies have shown no or little effect of birthweight on blood pressure. Confounding and selection bias have been a problem in some of the studies. The ideal approach for avoiding selection bias is to conduct a prospective cohort study with minimal loss during follow-up. Therefore, the relationship of birthweight with blood pressure was examined in a cohort born during 1992-1993. Methods A cohort of 214 babies, born to usual residents in 10 villages of Haryana state in India on weekdays from September 1992 to November 1993 whose birthweight had been recorded by a trained field worker within 24 hours of delivery, were followed up during 2000-2001. During the 7-8 year period, 17 children had died and 12 had migrated. A trained public health nurse examined the remaining 185 children and measured their weight, height, and blood pressure. Results Mean birthweight was 2.7 kg and 21.1% had low birthweight (<2500 g). Current weight, height, and body mass index (BMI) were associated with birthweight (P < 0.05). Systolic blood pressure (SBP) increased significantly with rise in current weight and height. Relationship of SBP with birthweight seems to be a U-shaped distribution. Compared with the middle birthweight tertile group, in the lowest and highest birthweight groups boys have higher SBP in the higher BMI category (greater than or equal to13.5 kg/m(2)) and girls have higher SBP in both lower and higher BMI categories. ANOVA analysis showed that SBP and diastolic blood pressure (DBP) were not significantly different in birthweight tertile groups among boys, but for SBP the difference was statistically significant among girls (P = 0.03). However, multivariate linear regression analysis that included socioeconomic status and current anthropometeric measures (weight, height, BMI) revealed that birthweight is not associated with SBP or DBP, and the interaction between birthweight and gender was also not significant for SBP and DBP (P = 0.09). Conclusion The findings of this population-representative cohort from rural India with 94% follow-up suggest that birthweight is not associated with blood pressure among 7-8 year old children.