Parents’ lifestyle choices may help determine their children’s blood pressure, even before their kids are born, a new study suggests.

UK and Australian researchers found that 5-year-olds whose mothers smoked during pregnancy had higher blood pressure than the children of non-smokers, while those who had been breastfed for at least 6 months had lower blood pressure than those who were breastfed for a shorter time.

In addition, both parents’ weights influenced their child’s blood pressure, which rose in tandem with mom’s and dad’s body mass index (BMI).

Because childhood blood pressure “tracks” into adulthood, the findings indicate that high blood pressure prevention needs to begin early, according to Dr. Debbie A. Lawlor and her colleagues.

One of the most important - and earliest - ways to do this is for expectant mothers to avoid smoking during pregnancy, said Lawlor, of the University of Bristol in the UK.

“We hope that these findings would give more motivation…for young women who smoke to quit, and for those who do not smoke not to take it up - both for their own health and that of their offspring,” she told Reuters Health.

A healthy diet and exercise, for the whole family, also appear key, Lawlor and her colleagues report in the current issue of the American Heart Association’s journal Circulation.

The researchers found that parents’ BMI - before pregnancy for mothers, and during pregnancy for fathers - was related to their 5-year-old’s blood pressure, as was the child’s own BMI.

Although these associations may reflect a genetic predisposition to obesity and high blood pressure, the investigators note, “they are also likely to be strongly influenced by family diet and physical activity levels.”

The study involved nearly 3,900 Australian children who were followed from their first days of life until age 5 to see which prenatal and early-life factors were associated with childhood systolic blood pressure, the top number in a blood pressure reading.

Lawlor’s team found that systolic pressure was an average of one point higher among children whose mothers smoked during pregnancy, compared with those born to women who did not smoke.

Although this effect and those of other individual early-life factors were “modest,” together they made an important contribution to systolic blood pressure at age 5, the researchers point out.

An adult can counter prenatal and childhood influences on blood pressure by adopting a healthy lifestyle, Lawlor said. But she added that research has uncovered the beginnings of clogged arteries even in children, and this may not be completely reversed by healthy habits later in life.

“The message,” she said, “has to be that healthy lifestyles - no smoking, healthy diets, physical activity - are important at all ages.”

SOURCE: Circulation: Journal of the American Heart Association, October 19, 2004.