High pressure jobs like nursing can increase young women's risk of heart disease and younger women appear to be more vulnerable, scientists said Thursday.

It is already known that having stressful or demanding jobs can lead to higher heart risks but previous research has largely focused on men.

In this study, researchers from Denmark assessed the impact of work pressure and degree of personal influence in the workplace on the heart health of more than 12,000 nurses.

The nurses were all aged between 45 and 64 in 1993, when they were questioned about daily work pressures and about how much they felt they had control over their work. Their health was then tracked for 15 years using hospital records.

The results, published in the journal Occupational and Environmental Medicine, showed that nurses who said their work pressures were a little too high were 25 percent more likely to develop heart disease as those who said work pressures were manageable and appropriate.

Those who felt work stress was much too high were 35 percent more likely to have heart disease after other risk factors like smoking and lifestyle were taken into account.

But when the findings were analyzed by age they showed that nurses under age 51 were at significant risk of heart disease.

A separate analysis of this age group showed those who felt they were under moderate work pressure were 60 percent more likely to have heart disease while those who said they faced excessive pressures were almost twice as likely to have it.

These findings held true even after taking account of other risk factors.

"This study adds to the previous body of evidence suggesting harmful effects of excessive psychological demands at work on cardiac health, but is one among very few that demonstrates the effect among women," the researchers, from Glostrup University Hospital in Denmark, wrote in the study.

They said more studies were now needed to identify what was contributing to the perceived high work pressure.

Heart disease is the leading killer of men and women in Europe, the United States and many other rich nations. Together with diabetes, cardiovascular diseases accounted for almost one third of all deaths around the world in 2005, according to the Geneva-based World Health Organization.

June Davison, a cardiac nurse at the British Heart Foundation, said that feeling under pressure at work meant stressed employees may pick up unhealthy habits and add to their risk of developing heart problems.

"Pressurized workers may reach for cigarettes, snack foods and alcohol to make themselves feel better," she said in an emailed comment. "If you feel under pressure you should try and tackle it in a positive way and get active during work hours."