Animal studies have shown that undernutrition before birth programmes persisting changes in a range of metabolic, physiological and structural parameters. Studies in humans have shown that men and women who had birth weights at the lower end of the normal range, who were thin or short at birth, or who were small in relation to placental size, have increased rates of coronary heart disease. This article suggests how fetal undernutrition at different stages of gestation may be linked to these patterns of early growth. Adaptations by the fetus to undernutrition are associated with changes in the concentrations of fetal placental hormones. Persisting changes in the level of hormone secretion and tissue sensitivity may link fetal undernutrition with adult disease.