NEW YORK — High blood pressure in younger people may be particularly hazardous for women, a new study suggests. The study found that women — but not men — with even mildly elevated blood pressure in their early 40s may be at substantially increased risk for later coronary disease and death.

In 1992, Norwegian researchers began studying 12,329 men and women whose average age was 41. They tracked their blood pressure and cardiovascular health for an average of 16 years.

At the start, high blood pressure was much less common in women than in men: 25 per cent of women and 35 per cent of men had stage 1 hypertension, which the American Heart Association defines as a reading of 130/80 to 139/89. (A reading under 120/80 is considered normal.)

Fourteen percent of women and 31 per cent of men had stage 2 hypertension, defined as 140/90 or higher. The women also had fewer risk factors for heart disease: They tended to have lower body mass index (BMI) scores and lower cholesterol levels, and fewer of them were smokers.

During the follow-up period, 1.4 per cent of the women and 5.7 per cent of the men had been hospitalised with or died from cardiovascular disease.

Compared with women who had normal blood pressure at the start of the study, those with stage 1 hypertension had more than double the risk of heart disease. In men, this association was statistically insignificant. The study, in the European Journal of Preventive Cardiology, controlled for diabetes, BMI, cholesterol, smoking and physical activity.

The authors acknowledge that the study had limitations. It was done in a small geographic area in Norway, and the subjects were primarily Caucasian. Moreover, the researchers had no information about hypertension treatment or the use of cholesterol-lowering drugs during the follow-up period.

Still, “the emerging evidence is that hypertension is worse for female hearts than for male hearts,” said the lead author Ester Kringeland, an internal medicine specialist at the University of Bergen in Norway, “and the risk starts at a lower blood pressure level in women.”

Dr Joyce M Oen-Hsiao, an assistant professor of medicine at Yale who was not involved in the work, said, “It’s a well-designed study. Most of us just look at risk factors, and we never really break it down by gender. That’s the novelty of this paper — that there’s a statistical difference between men and women. And if we can replicate this finding in our more diverse population, it will change primary prevention.”

Current American Heart Association guidelines say that in otherwise healthy people, high blood pressure up to 130/80 can usually be managed with lifestyle changes. For readings from 130/80 to 139/89, the group recommends antihypertensive drugs, but only for people with other cardiovascular disease risk factors. At 140/90 or higher, medication is indicated in almost all cases. But the guidelines make no distinction between men and women.

Dr Kringeland said that one reading, or a reading with a home blood pressure monitor, is not enough to make a diagnosis.

“A doctor has to take three readings, then average the last two. And to diagnose hypertension, you need at least two visits to the doctor.”

The question of whether a healthy woman in her 40s with a reading of 130/80 should be treated with antihypertensive drugs is still not settled.

“In some women — those with diabetes, for example — treatment is indicated even at this level,” Dr Kringeland said. “But in women who are otherwise healthy? We don’t have the answer yet. Blood pressure medicines have side effects, and you have to look at the risk-benefit ratio. We need more research about cardiac disease in women.”

This article originally appeared in The New York Times.