#78 Birth weight modifies the relationships between systolic bloodpressure, pubertal development, and body mass in adolescents

PURPOSE: Studies have shown that systolic blood pressure (SBP) is positively associated with body size and sexual maturation, but inversely associated with birth weight during childhood. The aim of the this longitudinal study was to examine the moderating effects of birth weight on the associations of SBP with pubertal development and body mass in Caucasian and African American children. METHODS: One hundred and thirty nine children aged 4 to 12 years at the start of the study were followed up annually for 3 to 5 years with an average of 4 repeated measures for each subject (n = 560 observations) in Birmingham, Alabama. Characteristics measured annually included blood pressure, Tanner stage, and body composition from dual energy x-ray absorptiometry. RESULTS: SBP was inversely correlated with birth weight (r = −0.10, P = 0.02), especially in Caucasian children (r = −0.16, P = 0.002). Larger BMI was significantly associated with higher SBP (p < 0.001). Lower birth weight was significantly associated with a faster increase of SBP with respect to the increase of BMI (β = −0.4, p < 0.05). In contrast, lower birth weight was significantly associated the slower increase of SBP with pubertal development (β = 1.3, p < 0.10). CONCLUSION: The findings from this longitudinal study suggest that birth weight may modify the effects of body size and pubertal development on the increase of SBP during adolescence.