Elevated systolic blood pressure in preterm very-low-birth-weight infants ≤3 years of life

Abstract

Preterm, very-low-birth-weight neonates (≤1500 gm, VLBW) exhibit elevated systolic blood pressures (SBP) in adolescence and adulthood; however, the age of onset and causes are unknown. We assessed SBP in a cross-sectional study of VLBW infants at 1, 2 and 3 years of age (n = 40 per cohort). SBP was manually measured using Doppler amplification (observed), and calm values were compared to reference ranges used for clinical purposes (expected). SBP was converted to age-, gender- and height-specific z-scores (SBPz). Perinatal variables and growth parameters measured between 6 and 36 months were assessed as predictors of an elevated SBP. Observed SBP and SBPz exceeded the expected value at each age (P < 0.01); for example 1 year SBP was 94 ± 10 (standard deviation) vs. 85 ± 3 mmHg, respectively. Although the expected SBP rose from 85 ± 3 to 90 ± 3 mmHg with advancing age (P < 0.05), VLBW SBP was unchanged (P > 0.1), averaging 93 mmHg across ages. Height and weight z-scores were below expected (P < 0.01), while weight-for-height z-scores exceeded zero at 6, 12 and 24 months (P < 0.05). Male subscapular skinfold thickness:abdominal circumference ratio decreased with advancing age, paralleling the decreases in SBPz. The VLBW neonates demonstrated an elevated SBP as early as 1 year of age. Although predictive perinatal variables were not identified, gender-specific relationships between infant growth and SBP were observed.