Iron (Fe) deficiency anaemia during pregnancy results in an increased risk of peri-natal mortality and morbidity and is a significant factor for increased risk of disease in later life. Consequently we have developed a rat model to study the relationship between maternal Fe deficiency and postnatal growth and blood pressure in the offspring. Weanlings were fed a control or Fe deficient diet prior to and throughout pregnancy. At term, all pups were cross fostered to control fed dams and weaned onto control diet. At birth pups from deficient dams had a greater mortality rate, were smaller and had reduced haematocrit and liver Fe levels. They also had larger hearts, smaller kidneys and spleens and unchanged livers (relative organ weight). The pups grew normally. At 6 weeks, male pups from deficient dams had a higher and females a lower blood pressure than their normal counterparts. At 10 and 16 weeks blood pressure in the males from deficient dams was still raised and in the females blood pressure had increased and was now greater than controls. The haematocrit was lower in males throughout the 16 weeks and in females until 10 weeks of age. There was no significant difference in the offspring's liver Fe stores at 6, 10 or 16 weeks. Duodenal Fe uptake in both the Fe deficient mother and newborn offspring was significantly increased. By cross fostering, we have eliminated confounding factors, such as maternal anaemia during lactation and show, unequivocally, that prenatal nutrition is critical for the development of normal post- natal function.