They also collected data from birth records about their babies' birth weight, whether the women smoked during pregnancy, and their age at delivery.
About 18 years after giving birth, the mothers now at an average age of 48 had a follow-up visit at a health clinic. At that time, the women's height, weight, waist size, blood pressure, and blood glucose were all measured. They also tested lipid (blood fat) and insulin levels, which can both influence heart disease risk.
The research appears in Circulation: Journal of the American Heart Association.
Researchers found that women who gave birth to babies who were significantly larger than average tended to have larger waists and higher glucose concentrations in their blood. Mothers who had babies who were significantly smaller than average had higher blood pressure.
Scientists also calculated each woman's risk of heart disease in the next 10 years.
They found that pregnancy-related high blood pressure (preeclampsia) was linked with a 31% greater risk of having heart disease in middle age. It might be a better predictor of future heart problems than any other pregnancy-related complication.
"Pregnancy may provide an opportunity to identify women at increased risk of heart disease while they are relatively young," researcher Abigail Fraser, PhD, says in a news release. She is a research fellow at the School of Community and Social Medicine at the University of Bristol in England.
Knowing earlier in life if a woman has a greater likelihood of heart disease may give health professionals more time to discuss with her heart-healthy lifestyle changes or other treatments needed to reduce this risk.