ObjectivesTo examine the relationship between indicators at birth and adult blood pressure and risk for developing hypertension at two age levels.DesignOriginal midwife records of 438 women born at term participating in a prospective population study in Göteborg, Sweden with blood pressure and hypertension assessment at both 50 and 60 years of age.ResultsSystolic blood pressure at both age levels showed a U-shaped relationship to weight and length at birth. Hypertension prevalence at 60 years was significantly and inversely related to both weight and length at birth, but not at 50 years. Significantly higher risk for hypertension was found in the lowest birth weight quintile [odds ratio (OR) = 2.0, 95% confidence interval (CI) 1.1–3.8] and lowest birth length tertile (OR = 1.8, 95% CI 1.1–3.0), in relation to the middle quintile/tertile, with or without adjustment for adult body size (as body mass index), at 60 years but not at 50 years. At 50 years, hypertension risk decreased by 3% (95% CI 0.92–1.01) for every 100 g increase in birth weight and 6% (95% CI 0.83–1.05) per cm birth length. At age 60 years, hypertension risk decreased by 4% (95% CI 0.92–0.99) per 100 g birth weight and 10% (95% CI 0.81–0.99) per cm length.ConclusionsSize at birth was a predictor of hypertension risk in women at 60 years but not 50 years. This study supports the hypothesis that poor fetal growth, as measured by low weight or length at birth, may contribute to the development of hypertension in later life and that this relationship became stronger with age.