The 'foetal origins' hypothesis (Barker hypothesis) proposes that undernutrition of the foetus during critical periods of development increases the risk of coronary heart disease in later life. The Dutch famine caused by the second World War in the winter of 1944--although a historical disaster--provides a unique opportunity to study effects of undernutrition during gestation in humans. The health of people born around the time of the Dutch famine, in the Wilhelmina Gasthuis in Amsterdam, of whom detailed birth records exist, was assessed. There were indications that chronic diseases in later life are associated with prenatal undernutrition. The associations with undernutrition, however, depend upon the time of occurrence during gestation. Our findings are compatible with the conclusion that maternal malnutrition during gestation may permanently affect adult health without affecting the size of the baby at birth. This may imply that adaptations that enable the foetus to continue to grow may have adverse consequences for health in later life.