Sex-specific programming of cardiovascular physiology in children

Increasing evidence suggests that adverse prenatal environments, as indicated by low birth weight, cause long-term changes in cardiovascular physiology that predispose to circulatory disease. The mechanisms are poorly understood, most human studies have been carried out in adults and little is known about early pathophysiological changes. Therefore, we have assessed the relationship between birth weight and cardiovascular physiology in children.

In 140 healthy boys and girls (aged 7-9 years), born at term and followed prospectively, we continuously recorded blood pressure, electrocardiograms and cardiac impedance before, during, and after 10 min of psychosocial stress (Trier Social Stress Test for Children). In boys, an association of lower birth weight with higher resting systemic arterial pressure (β = -6.8 mmHg/kg, P= 0.03) and a trend towards higher vascular resistance (β = -87 dyne s/cm(5)/kg, ns) were substantially strengthened following stress (β = -9.5 mmHg/kg, P= 0.003 and β = -139 dyne s/cm(5)/kg, P = 0.02, respectively). In girls, lower birth weight was associated with a shorter pre-ejection period (β = 8.0 ms/kg, P = 0.005) and corrected QT interval (β = 11.9 ms/kg, P = 0.003) at rest and little changed by stress.

Smaller size at birth is associated with sex-specific alterations in cardiac physiology; boys had higher systemic vascular resistance and girls had increased cardiac sympathetic activation.