The performed analysis of the morphology of cardiomyocytes and myocardial vascular bed in 12 pregnant rats and 16 newborn pups exposed to the hemic hypoxia induced by NaNO 2 revealed some similar degenerative and destructive changes which were more pronounced in pups. The main morphological characteristics of hypoxic myocardial damage in pregnant and newborn rats were presented in the form of phenomena of mixed dystrophy, swelling and destruction of endothelial cells and contractile cardiomyocytes along with the lysis of myofibrils, perivascular edema, capillary hyperemia, emptiness and spasm of the arterioles and contracture changes. Revealed pathological changes in the myocardium reflect the development of the myocardiodystrophy processes in pregnant rats and newborn pups.