Introduction Low birth weight has been associated with an increased risk of hypertension in children. Less clear is whether high birth weight is also associated with risk. We evaluated overall and age-specific risks of primary hypertension in children and young adults associated with birth weight and birth weight for gestational age. Methods We conducted a population-based case-control study using linked Washington State birth certificate and hospital discharge data from 1987 to 2003. Cases were persons hospitalized with primary hypertension at 8-24 years of age (n = 533). Controls were randomly selected among those born in the same years who were not hospitalized with hypertension (n = 25,966). Results Birth weight was not related to risk of primary hypertension overall, except for a suggestion of an increased risk associated with birth weight ≥4500 g relative to 3500-3999 g (odds ratio (OR) 1.55; 95 % confidence interval (CI) 0.96-2.49). Compared to children born appropriate weight for gestational age, those born small (SGA) (OR 1.32; 95 % CI 1.02-1.71) and large for gestational age (LGA) (OR 1.30; 95 % CI 1.00-1.71) had increased risks of primary hypertension. These overall associations were due to increased risks of hypertension at 15-24 years of age; no associations were observed with risk at 8-14 years of age. Discussion In this study, both SGA and LGA were associated with increased risks of primary hypertension. Our findings suggest a possible nonlinear (U-shaped) association between birth weight for gestational age and primary hypertension risk in children and young adults.
Keywords: Birth weight; Children; Hypertension; Young adults.