Much epidemiological evidence has linked low birthweight with late cardiovascular risk. We measured aortic wall thickness (a marker of early atherosclerosis) by ultrasonography in 25 newborn babies with intrauterine growth restriction and 25 with normal birthweight. Maximum aortic thicknesses were significantly higher in the babies with intrauterine growth restriction (810 microm [SD 113]) than in those without (743 microm [76], p=0.02), more so after adjustment for birthweight (300 microm/kg [45] vs 199 microm/kg [29], p<0.0001). Newborn babies with growth restriction have significant aortic thickening, suggesting that prenatal events might predispose to later cardiovascular risk.