American Journal of Epidemiology Advance Access published online on March 10, 2007
American Journal of Epidemiology, doi:10.1093/aje/kwm028
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ORIGINAL CONTRIBUTIONS |
Growth Trajectory Matters: Interpreting the Associations among Birth Weight, Concurrent Body Size, and Systolic Blood Pressure in a Cohort Study of 378,707 Swedish Men
1 Department of Social Medicine, University of Bristol, Bristol, United Kingdom
2 Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom
3 Department of Public Health Sciences, Karolinska Institute, Stockholm, Sweden
4 Division of Epidemiology, Stockholm Center of Public Health, Stockholm, Sweden
Correspondence to Dr. Finn Rasmussen, Child and Adolescent Public Health Epidemiology Group, Department of Public Health Sciences, Karolinska Institute, Norrbacka Building, SE-171 76 Stockholm, Sweden (e-mail: finn.rasmussen{at}ki.se).
Received for publication August 14, 2006. Accepted for publication December 5, 2006.
The interpretation of the inverse association of birth weight with adult blood pressure after adjustment for concurrent size has been debated. In a large sample (n = 378,707) of Swedish men aged 18 years, born between 1973 and 1984, the authors found considerable variation in birth weight within strata of identical adult body mass index (to the nearest kg/m2; range: 17–33 kg/m2), weight (nearest kg; range: 52–100 kg), and height (nearest cm; range: 164–196 cm). The regression coefficient of systolic blood pressure on birth weight was inverse and the same within strata of identical body mass index (pinteraction = 0.80), weight (p = 0.79), and height (p = 0.35). When the analyses were restricted to those who were born between 39 and 41 weeks' gestation, consistent inverse associations remained within strata of identical adult size. Findings were similar when hypertension (rather than mean systolic blood pressure) was the outcome. These findings demonstrate that, for male babies who grow to be the same size at age 18 years, those who were of lower birth weight have on average higher blood pressure and a greater risk of hypertension. They suggest that growth between conception and early adulthood has relevance to understanding the etiology and, hence, prevention of high blood pressure.
adult; birth weight; blood pressure; body mass index; body weight; growth; hypertension; male
Abbreviations: CI, confidence interval; SD, standard deviation