Women, who have given birth to four or more children, are nearly twice at a risk of developing a heart disease, according to a University of Texas study.

Researchers said that the more number of times women get pregnant, the higher is the risk of them developing narrow and thickened arteries that can lead to stroke and heart attack.

Pregnancies trigger cardiovascular disease in women. For example - the volume of blood pumped through the heart rises by 50 percent.

In the study, researchers set out to determine whether number of deliveries is linked to cardiovascular disease.

For the study, researchers surveyed 1,644 women, aged 45 years on an average, from the Dallas Heart Study. They measured Coronary artery calcium (CAC) and aortic wall thickness (AWT) to collect evidence of narrowing and hardening in the heart and artery walls in women.

The researchers found that women, who gave birth to four or more children, had nearly twice the risk of having abnormal CAC or AWT than those with two or three births.

"Our findings add to the growing body of evidence that the changes associated with pregnancy may provide insight into a woman's future cardiovascular risk and deserves further attention," Dr Monika Sanghavi, lead author of the study, said in a press release.

The researchers also found that women, who had no children or just one child, faced a heightened risk of displaying narrowed or hardened arteries. But, they believe that they may have included some women with an underlying condition of polycystic ovaries.

Previous studies showed that women with polycystic ovaries, have an elevated risk of high blood pressure and cholesterol that can cause heart disease and stroke.

"Pregnancy has been called 'nature's stress test,' and for good reason. It may also help identify women who are at increased risk for heart disease, even though right now they may not have any risk factors. The benefit of pregnancy is that it occurs relatively early in a woman's life and allows for early intervention for those at higher risk," Sanghavi said.