Increased catecholamines and heart rate in children with low birth weight:: perinatal contributions to sympathoadrenal overactivity

Background: Low birth weight is associated with cardiovascular disease. The underlying mechanisms are unknown. We hypothesized that perinatal stress alters autonomic regulation of the cardiovascular system. In this study, catecholamines, heart rate (HR) and blood pressure (BP) were measured in healthy children with low birth weight. Methods: This clinical study included 105 children (mean age 9.6 years) in three groups; born at term with normal birth weight (controls, n = 37), born at term but small for gestational age (SGA, n = 29) and born preterm (Preterm, n = 39). Dopamine, adrenaline and noradrenaline were determined in urine. HR and BP were measured at rest, during an orthostatic test and after a mathematical mental stress test. Results: Children in the Preterm and SGA groups excreted higher levels of catecholamines when compared with controls. HR (mean [SD] values) were higher at rest and after mental stress in Preterm (at rest 76 [9] and after mental stress 82 [12] min(-1)) and in SGA (79 [8] and 82 [10]) when compared with controls (70 [9] and 75 [9]). HR correlated with urinary catecholamines (r = 0.24-0.27, P < 0.05). Blood pressures measured at rest, during orthostatic testing and after mental stress did not differ between the groups. Conclusion: Preterm birth and fetal growth restriction are associated with increased sympathoadrenal activity in childhood, as indicated by stress-induced increases in HR and urinary catecholamines. These findings suggest that the cardiovascular control is differently programmed in these children with possibly higher risk of developing hypertension in adulthood.