Systolic blood pressure in a population of infants in the first year of life: the Brompton study.

Systolic blood pressure (BP) was measured by the Doppler technique and random zero sphygmomanometer in a sample of infants between the ages of 4 days (n = 1,740) and 1 year (n = 1,338). Mean systolic BP rose from 76 mm Hg at age 4 days to 96 mm Hg at age 6 weeks in babies awake, and showed little further variation at 6 months and 1 year. The BP was approximately 6 mm Hg higher in babies awake than asleep. Blood pressure was nearly normally distributed at all ages and the 95th percentile for BP of babies awake was 95 mm Hg at 4 days and 113 mm Hg between 6 weeks and 1 year. A comparison of intra-arterial and Doppler BP confirmed that both inflation bag length and cuff width are important for accurate measurement.