Data from the Dutch Famine Birth Cohort Study were analyzed to assess the influence of acute famine on the relation of maternal weight gain to birth weight, length, and ponderal index. Records were examined for 734 women receiving at least one month of prenatal care and delivering live-born singleton females at the University of Amsterdam Teaching Hospital between August 1944 and April 1946. This period preceded, encompassed, and followed the Hunger Winter, a severe famine. After adjusting for covariates, weight loss or low to moderate (< or = 0.5 kg/week) weight gain was strongly associated with (p < 0.001 for each model) with offspring birth weight, length, and ponderal index and with trimester of famine exposure. At weight gains greater than 0.5 kg/week further weight gain was not associated with birth size. Among women losing weight or gaining < or = 0.5 kg/week the association between third-trimester weight change and birth weight among mother-daughter pairs exposed to famine in early or mid-pregnancy was stronger than the association observed among the unexposed cohort or among those exposed only late in pregnancy. Our results suggest that acute maternal nutritional deprivation affects fetal growth only below a threshold and that, conversely, even after a famine period offspring birth size does not respond in a linear fashion to ad libitum maternal feeding.