ANTENATAL STEROID EXPOSURE AND BLOOD PRESSURE IN CHILDHOOD

我们假设在极低出生体重（VLBW;1501g）婴儿中暴露于产前糖皮质激素（ANCS）

We hypothesize that exposure to antenatal glucocorticoids (ANCS) in very low birth weight (VLBW;1501g) infants is associated with elevated blood pressure at 14 years of age. ANCS are frequently given to mothers who are expected to deliver prematurely to improve survival of premature infants. However, ANCS have been associated with elevated blood pressure at 14 years of age. Childhood blood pressure is correlated with blood pressure in adulthood, and the latter influences the risk of cardiovascular morbidity. Among VLBW babies, both the survival rate and the rate of exposure to ANCS are high; thus, the proposed research is pertinent to a significant public health concern. Supporting the proposed link between ANCS and elevated blood pressure in adulthood, animals studies indicate that ANCS alter the developing kidney and brain, possibly by decreasing the activity of the renin-angiotensin system (RAS). These alterations lead to lifelong changes in kidney structure and function and altered cardiovascular control, predisposing the adult to hypertension. The subjects for the proposed study are VLBW children who were singleton births, born 1992-1995, cared for in our intensive care nurseries, and followed in our out-patient neonatal follow up clinic through one year adjusted age. In this sample the frequency of ANCS exposure is 47%. We propose measurements of the following: 1) resting blood pressure, height, and weight, at 3 visits in the year after the child's fourteenth birthday, 2) ambulatory blood pressure, 3) blood pressure response to exercise and cold stress, 4) heart rate variability, 5) salivary cortisol, 6) level of fitness and physical activity, 7) body composition using DXA scans, 8) microalbuminuria, 9) elements of the RAS in the urine and blood, and 10) estimated glomerular filtration rate. Data on perinatal exposures and growth through one year adjusted age will be obtained from medical records and a computerized database. Multivariate analyses will be used to estimate the difference in blood pressure between children exposed to ANCS and those not exposed to ANCS, adjusting for potential confounders and a number of known correlates of blood pressure.