Abstract 160
Aim: To relate blood pressure (BP) in a selected low birthweight (LBW) group to renal size and renal artery blood flow velocity. Methods: All LBW (<2500g) infants (n =3456) born in South East Thames region (SETRHA), UK from 1.9.92 to 31.8.93 were identified at birth. Maternal and infant's antenatal, perinatal and neonatal details had been recorded prospectively by an obstetrician. Sixty of these infants were randomly selected to have a renal ultrasound scan to measure renal size and renal artery blood flow velocity (RBFV) at age two to three years. BP was measured using a portable Dinamap 8100™ machine. The infants were divided into SGA (birthweight <10th centile) and AGA (birthweight ≥ 10th centile) subgroups. Results: The SGA group of babies (n=28) tended to have lower total renal volumes and (RBFV) though not statistically significantly different from that of the AGA babies (n=32). On multivariate analysis, confounding for perinatal and sociodemographic factors, the mean arm diastolic BP and ankle BP measurements were lower in children with greater total renal volumes (p=0.018 & p=0.0026) and mean systolic and diastolic BP also fell with increasing gestational age (p=0.032& p=0.036). By contrast, BP was higher in infants of higher birthweight(p =0.027) and those requiring neonatal mechanical ventilation (p=0.002). A relationship between BP and the district of residence of the parents, presumably reflecting the effect of social factors was shown in this group as well as in a concurrent population based LBW study. Conclusion: Perinatal factors such as growth restriction appear to affect the BP of LBW infants at 2-3 years of age. Infants with better grown kidneys and those born at a later gestational age had lower BP recordings. These findings suggest that cardiovascular morbidity might be initiated in early life but further investigation is required to demonstrate the relationship to later life BP. Socio-economic disadvantage and increased perinatal morbidity were also associated with higher BP levels.
