Women who give birth to four or more children are more likely to have cardiovascular changes that can be early indicators of heart disease, a new study by Indian-origin scientists has found.
“This study adds to a body of evidence that pregnancy, which generally occurs early in a woman’s life, can provide insight into a woman’s future cardiovascular risk,” said Dr Monika Sanghavi, Assistant Professor of Internal Medicine at University of Texas Southwestern Medical Center.
Using data gathered from 1,644 women in the Dallas Heart Study, researchers compared the number of live births reported by women in the study with their coronary artery calcium (CAC) levels and aortic wall thickness (AWT).
High levels of coronary artery calcification and thicker aortic walls are markers of heart disease that show up before symptoms develop.
Women were divided into three groups: One or no live births, two to three live births, and four or more live births.
Women who reported four or more live births had a 27 per cent prevalence of a high calcium score compared with 11 per cent among those with two to three live births. The trend was similar when looking at AWT measurements.
The associations were not affected by adjusting for socioeconomic status or traditional cardiovascular risk factors, suggesting that physiological changes associated with pregnancy may account for the change, Sanghavi said.
Further studies will be needed to identify the causes, but researchers said one possibility might be that women who have many pregnancies may have more visceral fat (fat around abdominal organs), which has been linked to increased heart disease risk.
Another possibility could be that increased cholesterol and higher blood sugar associated with pregnancy may lead to increased risk.
“During pregnancy, a woman’s abdominal size increases, she has higher levels of lipids in her blood, and higher blood sugar levels. Each pregnancy increases this exposure,” said Sanghavi, lead author of the study published in the European Journal of Preventive Cardiology.
The study also found slightly higher rates of high CAC and AWT measurements among women who had one or no children, compared with women who gave birth to two or three children.
“It’s likely that there is a different mechanism for the increased risk at the low end. Some of these women could have some underlying disease that prevents them from carrying births to term and increases their risk for heart disease,” Sanghavi said.
“We are learning that there are numerous physiologic changes during pregnancy that have consequences for future heart health,” said senior author Dr Amit Khera, Associate Professor of Internal Medicine, who directs the Preventive Cardiology Programme and holds the Dallas Heart Ball Chair in Hypertension and Heart Disease.