An excess of cardiovascular morbidity has been related to low birthweight. The aim of this study was to evaluate the relationship between low birthweight and levels of fibrinogen, lipoprotein(a), and albumin excretion rate, which are known risk factors for coronary artery disease. Seventy-two twins, with the same within-pair gender and normal glucose tolerance, were analyzed in order to avoid confounding factors, such as gestational age, birth order, or sex. Twins with the highest birthweights within the couple showed no significant difference of fibrinogen, lipoprotein(a), and albumin excretion rates compared with the twins with the lowest birthweights among the two co-twins. Moreover, no relevant correlation was found between birthweight and intra-pair birthweight differences and fibrinogen, lipoprotein(a), and albumin excretion rates. The lack of correlation between fibrinogen, lipoprotein(a), albumin excretion rate and birthweight, suggests that these factors do not contribute to the link between intrauterine malnutrition and increased cardiovascular risk.