Chronic stress during pregnancy can alter many factors and mechanisms that maintain the homeostasis of the organism. Neuropeptide Y has anxiolytic functions and is involved in modulating the stress response. The aim was to determine the effects of chronic stress on the plasmatic corticosterone andestrogen levels and the immunolabeling of the neuropeptide Y in the adrenal cortex of pregnant rats. The immobilization stress was applied from the fourth day of gestation until the sacrifice at days 12, 17 and 21 of the gestation. Immunostaining techniques, radioimmunoassay, stereological analysis and quantification of images were used. In the stressed pregnant rats significant increase in the plasmatic corticosterone levels at 12, 17 and 21 days ...