Birth weight and blood pressure in childhood: results from the Health Survey for England.
Findings of previous reports relating low birth weight with raised blood pressure in childhood and adolescence have been inconsistent. The present study uses cross-sectional data from a series of nationally representative annual surveys--the Health Survey for England--between 1995 and 2002, totaling a sample of 15 629 children aged 5 to 15. A significant negative relationship between birth weight, in quartiles or dichotomized as low (<2.5 kg) and normal (> or =2.5 kg) and systolic blood pressure was apparent. Linear regression analyses confirmed these findings. When current weight was included in the model, the strength of the relationship increased. An interaction term between birth weight and current weight was not significant. A life-course plot for those aged 13 to 15 (n=3900), converting the weight measurements at birth and as a teenager to standard deviation scores to make the regression coefficients comparable, showed the importance of weight gain on blood pressure (1 standard deviation increase in weight from birth to age 13 to 15 was associated with an increase in systolic blood pressure of 0.8 mm Hg). Separating those with low and normal birth weight demonstrated that the increase in weight from birth to adolescence had an effect on blood pressure in both those with low and normal birth weight. Postnatal changes in size have a more important effect on blood pressure in childhood and adolescence than birth weight. Reducing the prevalence of overweight among children may reduce their systolic blood pressure importantly and, particularly among children with lower birth weight, the prevalence of hypertension later in life.