To establish whether maternal smoking in pregnancy is associated with risk factors for cardiovascular disease (CVD) in mid-adulthood and whether associations are explained by postnatal influences. Participants were 8815 men and women in the 1958 British birth cohort, with data on CVD risk factors measured at 45 y. Maternal smoking was recorded at birth. Offspring of smokers had a higher adult BMI, waist circumference, blood pressure, HbA1c and triglycerides on average than offspring of non-smokers; females had lower HDL cholesterol levels. Total cholesterol was unrelated to maternal smoking. Associations were abolished after adjustment for postnatal influences across life, except for BMI and waist circumference: offspring of smokers had a BMI greater by 0.83 kg/m(2) on average than offspring of non-smokers and a 1.8 cm larger waist circumference. Mean BMI and waist circumference increased with number of cigarettes that the mother smoked, but were not elevated in offspring whose mother had quit smoking before or early in pregnancy. Adults exposed to tobacco in utero had a more adverse CVD risk profile in mid-adulthood which appeared to reflect a lifetime accumulation of postnatal influences; whereas their higher BMI and central adiposity may be due in part to intrauterine mechanisms. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.