Hypertension has become a serious public health problem in developed countries, yet the vast majority of cases have no known etiology. A recent hypothesis to account for blood pressure elevation in adults implicates low birth weight due to undernutrition in utero as a possible culprit. This hypothesis depends on the concept of "fetal programming," in which alterations in intrauterine physiology provoke long-lasting changes in fetal tissue development and the setting of homeostatic mechanisms. One possible mechanism for the improper setting of the fetal blood pressure homeostat is overexposure to maternal glucocorticoids. Although the studies have obtained somewhat mixed results, experiments on animal models and epidemiological studies of human cohorts have generated intriguing evidence suggesting that low birth weight may indeed precipitate chronically elevated blood pressure.