The im electroporated injection of a protease-resistant GH-releasing hormone cDNA into rat dams at 16 d gestation resulted in enhanced long-term growth of the F(1) offspring. The offspring were significantly heavier by 2 wk of age, and the difference was sustained to 10 wk of age. Consistent with their augmented growth, the plasma IGF-I concentration of the F(1) progeny was increased significantly. The pituitary gland of the offspring was significantly heavier and contained an increased number of somatotrophs and PRL-secreting cells, which is indicative of modification of cell lineage differentiation. These unique findings demonstrate that enhanced GH-releasing hormone expression in pregnant dams can result in intergenerational growth promotion by altering development of the pituitary gland in the offspring.