In a birth cohort from 1927 to 1937 consisting of 4,208 individuals, we examined the relation between complications in pregnancy and offspring adult mortality. Patterns of increased mortality were observed in the group of males whose mothers had experienced fever during pregnancy, i.e. with all-cause mortality (rate ratio 1.505; 95% CI 1.084-1.926; p=0.057), premature death (rate ratio 1.943; 95% CI 1.486-2.400; p=0.004), and with cancer (rate ratio 2.625; 95% CI 1.845-3.405; p=0.015). To our knowledge, this is the first study to report an association between fever in pregnancy and offspring mortality.