This study examined the effects of undernutrition in pregnancy on fetal and placental growth among infants born in 1944-1946 in The Netherlands, including infants born during the war-induced Dutch famine of 1944-1945. There was an increase in placental weight, but not in birthweight, in infants whose mothers' nutrition was compromised around conception or in the first trimester of pregnancy. Therefore, the placental index was also increased. Compared to pre-famine controls, the relative increase after first trimester exposure to undernutrition was larger in the northern part of the country (5.2 per cent, 95 per cent confidence interval 1.4, 9.0) where nutritional deprivation was presumably moderate compared to the west (3.5 per cent, 95 per cent confidence interval 0.2, 7.2) where nutritional deprivation was severe. The increase in placental weight is interpreted as compensatory for the reduction in maternal caloric intake. Whereas this suggests that pregnancy undernutrition can stimulate compensatory placental growth, the latter was only seen after first trimester undernutrition, which does not affect infant size at birth. For these infants, therefore, birthweight is not an appropriate proxy measure of undernutrition in pregnancy. These factors need to be considered in future studies relating pregnancy nutrition to adult health outcomes.