Adjustment for current weight and the relationship between birth weight and blood pressure in childhood

Objective To determine the role of current weight in mediating the relation ship between birth weight and blood pressure within the context of the 'fet al origins' hypothesis. Design Prospective cohort study of 2507 pregnant women and their singleton offspring, delivered live at term, in Perth, Western Australia between 1989 and 1992. The study commenced at 16 weeks gestation with serial weight and blood pressure measurements recorded through early childhood. Results Inverse associations were found between birth weight and systolic b lood pressure at ages 1,3 and 6. The effect of birth weight on systolic blo od pressure at age 6 reached statistical significance and was increased fou rfold in magnitude to -2.3 mmHg [95% confidence interval = (-3.3 to -1.3), P < 0.01] after adjustment for current weight. The interaction term for bir th weight and current weight was not statistically significant. Including i ntermediate weights did not produce a statistically significantly better mo del but did increase the magnitude of the estimated regression coefficient of birth weight on blood pressure, and only the birth weight and current we ight terms were significant. Conclusions Adjustment for current weight serves to highlight the relations hip between birth weight and blood pressure in childhood. Nevertheless, bir th weight, rather than birth weight adjusted for current weight, is still t he relevant predictor of later blood pressure within the context of the 'fe tal origins' hypothesis. J Hypertens 2000, 18:1007-1012 (C) Lippincott Will iams & Wilkins.