Systolic blood pressure differences in black, colored, and white infants.

Systolic blood pressure was measured in a random cluster sample of three-month-old black (n = 532), colored (n = 496), and white (n = 637) infants in Johannesburg, South Africa, by means of a Parks Doppler ultrasound device with a random zero sphygmomanometer. The study was conducted during a nine-month period in 1981. Major predictors of systolic pressure measurements were which fieldworker had taken the measurement and whether the child was quiet or agitated. After adjustment for predictors as necessary, the mean systolic blood pressure of black infants was about 2 mmHg higher than that of coloreds, which was statistically significant, with suggestive evidence that coloreds have a systolic pressure about 1 mmHg higher than that of whites. Findings at age three months may represent ethnic differences in blood pressure distributions of genetic origin.