Amplification of the association between birthweight and blood pressure with age: the Bogalusa Heart Study

OBJECTIVES Although low birthweight is associated with elevated blood pressure (BP) levels, whether the strength of this relationship is amplified with age is still debated. This study tested the hypothesis that the magnitude of the birthweight-BP association increases with age from childhood to adulthood. METHODS The study cohort included 6251 individuals (64.5% whites and 35.6% blacks, 50.0% males) enrolled in the Bogalusa Heart Study. Individuals were examined 1-15 times for BP from childhood to adulthood, with 24 363 observations. Information on birthweight and gestational age was obtained from Louisiana State birth certificates. RESULTS After adjusting for race, sex, age and gestational age, low birthweight (kg) was associated with higher SBP levels (mmHg) in adolescence (aged 12-17 years, regression coefficient β = -0.80, P = 0.004) and adulthood (aged 18-50 years, β = -1.34, P = 0.010). Adjustment for current BMI yielded considerably stronger association. Importantly, the magnitude of the birthweight-SBP relationship, measured as standardized β(unit = SD), was significantly amplified with increasing age, regardless of adjustment for current BMI and race. Further, the strengthened association (the increase in standardized β ranging 0.02-0.12) by adjustment for current BMI was closely related to the BMI-SBP and birthweight-BMI correlations, especially noted in childhood. CONCLUSION These findings on the potentiating effect of increasing age on the birthweight-BP relationship suggest that the fetal programming and the increasing cumulative burden with age of unhealthy lifestyle behaviors affect the development of adult hypertension in a synergistic manner.