Birth weight predicts subclinical orthostatic hypotension in children

BACKGROUND: Relatively low birth weight is associated with elevated heart rate and increased circulation of catecholamines and overall higher sympathetic activation in children. Increased levels of each of these variables in turn may promote poorer systolic blood pressure regulation in response to an orthostatic challenge. The present study examined the relationship between subsyndromal orthostatic systolic change in children and birth weights varying from 4 to 10 pounds. METHODS: Boys and girls (N=34) ranging in age from 7 – 10 years from a culturally diverse population were recruited. After lying supine for five minutes and again after about one minute of standing, blood pressure and pulse were measured. The greater the difference between standing minus supine systolic blood pressure, the stronger the response to orthostatic challenge. RESULTS: As birth weight increased, the systolic increase in blood pressure to an orthostatic challenge grew stronger. CONCLUSIONS: Increasing birth weight is associated with more efficient subsyndromal orthostatic blood pressure responses. Thus, increased heart rate and greater sympathetic nervous system activation found in low birth weight neonates are associated with poorer orthostatic blood pressure regulation that in turn is prognostic of cardiovascular difficulties and hypertension as well as cognitive and affective difficulties in childhood and in adulthood.