Blood pressure level, trend, and variability in Dunedin children. An 8-year study of a single birth cohort In a birth cohort of children in the Dunedin Multidisciplinary Health and Development Study in New Zealand, resting blood pressures were recorded biennially five times from age 7 to 15 years. Using previously described methods, we examined the level, trend, and variability of blood pressures in those children with at least three readings. The level, trend, and variability of height, weight, and body mass index were compared among six separate groups of children. Two groups were categorized on the basis of high systolic pressure levels, one with low variability and the other with high variability, which was thought to resemble adult labile hypertension. Two additional groups were categorized on the basis of increasing and decreasing blood pressure trends; the fifth group had consistently low blood pressures, and the sixth group consisted of the remaining children. There were significant differences among the groups for the level of all the physical measurements and for the trend of body mass index. No significant differences were found among the groups for gender or socioeconomic status. A parental history of high blood pressure, stroke, or heart attack was significantly more common in the first two groups. 