Heart Disease Risk Factors Rooted In Childhood

The team of British and Australian researchers, led by Dr Debbie Lawlor of the University’s Department of Social Medicine, looked at parental and early life characteristics and their association with blood pressure in 5-year-old offspring. The children of women who smoked during pregnancy had higher blood pressure compared to children of non-smokers, and parents’ weight also influenced blood pressure. Breast-feeding was associated with a lower blood pressure.

The findings from the study suggest a need to start heart disease prevention efforts early in life, rather than after risk factors have become well established.

The researchers reviewed parental and early-life factors that influenced blood pressure in children at the age of five. Interest in blood pressure at such an early age comes from the recognition that high blood pressure is a major risk factor for heart disease and that blood pressure in adults tends to follow the same pattern seen in childhood. Previous studies of blood pressure in childhood have tended to involve relatively few children, used different types of study designs, and produced inconsistent results.

This study involved more than 8,500 Australian women and their offspring enrolled in the Mater-University (Queensland, Australia) study of pregnancy and outcomes. The investigators evaluated a variety of variables for their potential influence on childhood blood pressure. The factors included ethnicity, smoking history, mother’s height and weight, father’s body mass index, family education and income. 3,864 offspring were examined at the age of five.

Children of women who had smoked throughout pregnancy had a systolic blood pressure (the first number in a blood pressure measurement) that was about 1 millimetre of mercury (mm Hg) – or point – higher at age five, compared to children whose mothers did not smoke during pregnancy. A comparison of women who stopped smoking during pregnancy with those who continued suggested that stopping during pregnancy could prevent the adverse effect on offspring blood pressure.

A mother’s age was also associated with higher blood pressure. A child’s systolic blood pressure was 0.7mm Hg higher for every additional five years of age in women at the time they gave birth.

Breast-feeding for at least six months was associated with lower blood pressure. Other factors associated with blood pressure were the mother’s weight and height, the father’s weight, and the child’s weight, height, and body mass at age five.

The findings have implications for childhood prevention strategies that might yield benefits into adulthood, the investigators concluded.

Dr Lawlor said: “Since childhood blood pressure tracks into adulthood, interventions aimed at early life risk factors – stopping smoking during pregnancy, breast feeding, prevention of obesity in all family members – may be important for reducing the population distribution of blood pressure, and thus cardiovascular disease risk.”

Dr Lawlor’s co-authors are Jake M Najman, Jonathan Sterne, Gail M Williams, Shah Ebrahim, and George Davey Smith.