Blood pressure in infant twins: birth to 6 months of age.

To describe the time course of the early development genetic variance for blood pressure, a cohort of twins is being followed from birth to 1 year of age. The present interim report describes systolic and diastolic blood pressure measurements for 102 twin pairs (39 monozygotic (MZ) and 63 dizygotic (DZ) in the newborn period and at 1, 3 and 6 months of age. Mean values for both systolic and diastolic blood pressure were similar regardless of race, sex, zygosity, or chorionicity. Statistically significant genetic variance was detected for systolic blood pressure at 6 months of age but not for diastolic blood pressure at any data point. The data are consistent with the hypothesis that genetic factors that determine within-family similarities of blood pressure may be detected early in life, and support the need for further investigation of both genetic and environmental determinants of blood pressure in young populations.