Capillary remodeling in infants born to hypertensive pregnancy: pilot study

Capillary rarefaction is pathognomonic of essential hypertension. We have previously shown significant capillary rarefaction in normotensive adult offspring of hypertensive parents, suggesting a familial predisposition in which capillary rarefaction represents a primary vascular abnormality that antedates the onset of sustained elevation of blood pressure (BP). We have recently reported that low-birth weight (LBW) infants, born at term or preterm, to normotensive mothers do not have capillary rarefaction at birth. We hypothesized that infants born to mothers with hypertensive disorders of pregnancy (HDP) would have significant capillary rarefaction at birth when compared to infants of normotensive mothers.

We studied 22 infants born to hypertensive mothers and compared them to 40 normal birth weight infants born at term to normotensive mothers. We used orthogonal polarized spectroscopy to measure basal (i.e., functional) and maximal (i.e., structural) skin capillary densities according to a well-validated protocol.

We found that term infants born to hypertensive mothers had significantly lower maximal capillary density (MCD) (mean difference of -5.0 capillaries/mm(2); P < 0.05). However, preterm infants with LBW born to hypertensive mothers tended to have higher basal and maximal skin capillary densities compared with term infants.

While the results in term infants are consistent with our belief that capillary rarefaction in essential hypertension is likely to be a primary vascular abnormality, the results in preterm infants may suggest that the intrauterine environment may exert some influences on the remodeling of the microcirculation which may delay the onset of capillary rarefaction in these infants.