Background: Increased prevalence of hypertension, ischaemic heart disease and stroke has been reported in subjects with impaired growth during fetal life and infancy. Blood pressure could mediate this relation. Indeed, reduced growth in fetal life and infancy has been associated with a raised blood pressure in children and adults. However, there is controversy about the relative importance of intrauterine environment and extrauterine adverse environment which can act throughout the life course. We therefore studied the relation between birth weight, which is known to be an indicator of fetal growth, and blood pressure in children and their parents. This association could thus be assessed in childhood before the external environmental influences became important, and in adulthood.
Methods: Seven hundred and fifteen healthy schoolchildren (379 boys) aged 3-12 years from primary schools, and 448 parents (252 women) aged 20-44 years, born at term, without hypertension or diabetes, were studied. Blood pressure and birth weight were measured. Birth weight was taken from the hospital records. Data were analysed by tabulation of means and linear regression and correlation techniques. Mean systolic and diastolic blood pressure were calculated according to birth weight and current weight as fourths of their distributions.
Results: There was a significant inverse relation between birth weight and systolic blood pressure both in children and adults. Current weight standardised regression coefficient showed a change of -2.68 mm Hg (95% Cl - 2.0 to 3.26, p = 0.027) for each Kg increase in birth weight in children, and -3.82 mmHg (95% Cl -3.21 to -4.39, p = 0.011) in adults. Within each current body weight group the reduction in mean systolic blood pressure from the lowest to the highest birth weight group was larger in adults (10.4 mmHg) than in children (4.1 mmHg). Adults but not children showed also an inverse relation between birth weight and diastolic blood pressure. Weight standardised regression coefficient was -3.0 mm Hg (95% Cl -2.45 to -3.62, p = 0.036).
Conclusions: Blood pressure in inversely related to birth weight in childhood. This relation becomes stronger in adulthood. Therefore, reduced growth during fetal life may be linked with an increased risk of developing hypertension and cardiovascular disease.