Newborn heart rate and blood pressure: relation to race and to socioeconomic class.

The effect of race and of socioeconomic class upon heart rate and systolic blood pressure distributions was examined in 247 full-term, appropriate birth weight newborns. For each newborn, heart rate and blood pressure measurements obtained during all of the non-rapid-eye-movement (NREM) periods of sleep in a single test session were each averaged. Heart rate was significantly faster in black newborns than in white newborns, and this racial difference in heart rate was similar in upper socioeconomic class subjects as in lower socioeconomic class subjects. Newborn systolic blood pressure did not vary as a function of race or of socioeconomic class. Systolic blood pressure correlated positively with the number of feedings from birth, the total fluid intake from birth, and the total sodium ingested from birth.