An inverse relation between blood pressure and birth weight among 5 year old children from Soweto, South Africa

Study objective-To examine the relation between birth weight and blood pressure at 5 years in a cohort of South African children. Design-Prospective cohort study. Participants-849 five year old children. Setting-Soweto, a sprawling urban area close to Johannesburg, South Africa, which was a designated residential area for people classified as "black" under apartheid legislation. Main results-Systolic blood pressure at 5 years was inversely related to birthweight (r=-0.05, p=0.0007), independent of current weight, height, gestational age, maternal age or socioeconomic status at 5 years. There was no relation between birth weight and diastolic blood pressure. After adjusting for current weight and height, there was a mean decline in systolic blood pressure of 3.4 mm Hg (95% confidence intervals 1.4, 5.3 mm Hg) for every 1000 g increase in birth weight. Conclusions These data from a disadvantaged urbanised community in Southern Africa extend the reported observations of an inverse relation between birth weight and systolic blood pressure. The study adds to the evidence that influences in fetal life and early childhood influence systolic blood pressure. Further research is required to assess whether efforts to reduce the incidence of low birthweight babies will attenuate the prevalence of hypertension in future generations.