Preterm birth attenuates association between low birth weight and endothelial dysfunction

Background - Low birth weight predisposes to later coronary disease. To further elucidate the mechanisms behind this association and their timing, vascular endothelial function - a key factor in early pathophysiology of atherosclerosis was studied in 54 infants born either before the third trimester or at term. Methods and Results - All subjects were studied at 3 months of postnatal age. A laser-Doppler technique was used to measure skin perfusion before and after transdermal iontophoresis of acetylcholine (ACh; an endothelium-dependent vasodilator). In infants born at term (n = 19; birth weight range: 2230 to 4205 g), maximum perfusion after ACh was 109 +/- 8 perfusion units ( PU, mean +/- SEM) in normal - birth weight controls compared with 56 +/- 13 PU among those who had been small for gestational age at birth ( P < 0.01). In infants born preterm ( n = 35; birth weight range, 722 to 1868 g), ACh induced similar perfusion responses among subjects appropriate for gestational age ( 113 +/- 16 PU) and in those small for gestational age at birth ( 109 +/- 19 PU). Conclusions - Impairment in human endothelial function associated with low birth weight occurs or emerges late in pregnancy. Very preterm birth attenuates this association. Different gene - environment interactions in the third trimester may contribute to this finding.