Maternal hormone manipulations and the development of obesity in rats

Pregnant rats were injected with either insulin, corticosterone, thyroxin, or saline during the third trimester (week) of pregnancy. Offspring from these groups had equivalent body weights at birth and at weaning. However, beginning at approximately seven weeks of age, male offspring in the insulin condition gained weight at significantly higher rates than their counterparts in the other three conditions. This increase in body weight was accompanied by a significant increase in carcass lipid content. These effects were not observed in female offspring.