Maternal cigarette smoking during pregnancy, low birth weight and subsequent blood pressure in early childhood

Given the widely acknowledged inverse relationship between birth weight and blood pressure, a raised blood pressure in the offspring of smoking mother s as compared to those whose mothers did not smoke, would be anticipated by virtue of the reduction in birth weight associated with smoking during pre gnancy. The objective of the present study was to test the hypothesis that maternal cigarette smoking during pregnancy has an effect on blood pressure in childhood independent of its effect on birth weight. Data was obtained from a prospective cohort study of 1708 pregnant women and their singleton offspring, delivered live at term, in Perth. Western Australia. commenced a t 16 weeks gestation with serial blood pressure measurements through early childhood. Statistically significant associations were found between matern al smoking Juring pregnancy and systolic blood pressure at age six, between birth weight and systolic blood pressure at ages three and six, and betwee n maternal smoking during pregnancy and birth weight. The relationship betw een birth weight and blood pressure in early childhood differed significant ly on the basis of maternal cigarette smoking or not during pregnancy. This differential relationship persisted after adjustment for the child's curre nt weight and socio-economic status. We concluded that intra-uterine exposu re to maternal cigarette smoking increased children's blood pressure at age one through to age six. This was not wholly attributable to an effect on b irth weight or confounding of the association between birth weight and subs equent blood pressure by the child's current weight or socio-economic facto rs. Furthermore, maternal smoking during pregnancy does not account for the acknowledged elevation in blood pressure associated with low birth weight. The present study is an exploration of a possible causal pathway underlyin g the birth weight/blood pressure association rather than simply ii confirm ation of such an association which has been detailed in many other papers. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.