Early Life Microcirculatory Plasticity and Blood Pressure Changes in Low Birth Weight Infants Born to Normotensive Mothers: A Cohort Study.

BACKGROUND: Capillary rarefaction (CR) is an established hallmark of essential hypertension (EH). The aim of this study was to examine early changes in capillary density (CD) and blood pressure (BP) in low birth weight (LBW) infants who are at risk of developing EH in later life.

METHODS: We studied 77 LBW infants and 284 normal birth weight (NBW) infants, all born to normotensive mothers in a longitudinal multi-centre study. Intravital capillaroscopy was used to measure functional (BCD) and maximal capillary density (MCD) at birth, 3 months, 6 months and 12 months.

RESULTS: We found that LBW infants, born pre-term and at term, had a significantly higher CD at birth, then underwent significant CR in the first 3 months culminating in a CD similar to that seen in NBW infants. NBW infants showed a gradual reduction in CD between birth and 12 months. Non-Caucasian ethnicity and preterm birth were significant predictors of a higher CD at birth. Systolic BP in NBW infants increased significantly from birth to 3 months, and we identified a significant negative correlation between systolic BP and MCD.

CONCLUSIONS: This study has identified a process of early "accelerated capillary remodeling" in LBW infants, which corrects their higher CD at birth. This remodeling is unlikely to explain the CR seen in adult individuals with, or at risk of developing EH. Further follow-up studies are required to determine the timing and mechanisms involved in CR which is likely to occur after the first year of life but before early adulthood.