Blood pressure in four and five-year-old children: the effects of environment and other factors in it's measurement--the Brompton study.

Systolic blood pressure was measured on a total of 1855 occasions in 1307 children aged four and five years, and compared with values obtained since birth in the same children. There was a rapid rise in blood pressure in the first month of life. The mean blood pressure then only rose from 93 mmHg at six months to 98 mmHg at five years. The 95th percentile was 113 to 114 mmHg over this period. In children aged four and five years, over the ranges studied, blood pressure was not importantly affected by place of measurement, time of day, time since previous meal, or ambient temperature. However, blood pressure was approximately 1.6 mmHg higher in winter than in summer (P less than 0.01). Nevertheless, it is unlikely that these factors are of significance when making clinical measurements. Blood pressure was correlated with weight at all ages. Between the ages of four and five years, the index, weight/height 1.70 was the best function of adiposity tested that was independent of age between four and five years. It is suggested that this or the Quetelet Index (weight/height2) are suitable indices for adjusting blood pressure for body build in children aged four and five years.