The relationship between birthweight and brachio-femoral pulse wave velocity in early infancy: findings from a British birth cohort (Baby VIP study).

BACKGROUND: In adults, pulse wave velocity (PWV) is regarded as a predictor of cardiovascular disease.(1) However, associations in infants are not well established. One study has linked neonatal aortic PWV, at 1-3 days, with birthweight and maternal blood pressure.(2) AIM: To examine the relationship between infant brachio-femoral PWV and size at birth. METHODS: Baby VIP study recruited 362 newborn babies from the Leeds Teaching Hospitals Trust, including 64 small for gestational age (SGA) (18%). PWV was measured non-invasively from each baby at a follow-up home visit 2-6 weeks after recruitment, using the Vicorder kit. Birthweight and other covariables were collected from the delivery and antenatal medical notes. Individualised birthweight centiles were calculated using the GROW-Centile calculator taking into account maternal weight, height, parity, ethnicity, gestational age and baby's sex.(3) RESULTS: Mean birthweight was 3329 g (standard deviation [sd] 632). Mean infant PWV was 6.7 m/s (sd 1.3). In univariable analysis, SGA babies had, on average, lower PWV by 0.4 m/s (95% confidence interval 0.0, 0.9, P = 0.04). This association persisted after adjusting for pregnancy factors including maternal smoking, pre-eclampsia, gestational diabetes, blood pressure at booking and 36 weeks, and infant factors including type of feeding, baby's age, position and whether asleep or awake at the time of measurement (0.5 m/s lower, 0.1, 0.9, P = 0.02). CONCLUSION: This study has demonstrated the feasibility and acceptability of measuring PWV in early infancy. SGA was associated with a lower PWV. These findings support the evidence linking SGA with cardiovascular indicators, even very early in life.