Researchers of a new study published in BMJ recently reported that women who experience any of five major pregnancy complications, including preterm birth and pre-eclampsia, have an increased risk of ischemic heart disease up to 46 years after delivery, emphasising that all major pregnancy complications should be recognised as lifelong risk factors for heart disease.

Despite major pregnancy-related complications experienced by about a third of women across the globe during their reproductive years being linked with higher future risks of heart disease, few studies have examined more than one outcome in the same group of women, preventing any firm conclusions to be drawn.

To address this, Swedish and American researchers set out to investigate the links between five major adverse pregnancy outcomes and long-term risks of ischemic heart disease in mothers.

They identified 2,195,266 women in Sweden with no history of heart disease who gave birth to a single live infant between 1973 and 2015 at an average age of 27.

Using nationwide medical records, the researchers tracked cases of ischemic heart disease from the delivery date to December 2018 (average follow-up time 25 years, up to a maximum of 46 years).

The researchers found that women who experienced any of the five major adverse pregnancy outcomes, namely, preterm delivery, small for gestational age at birth, pre-eclampsia, other blood pressure disorders of pregnancy, and gestational diabetes, were more at risk of developing ischemic heart disease.

Overall, ischemic heart disease was diagnosed in 83,881 (3.8%) women at an average age of 58 years, the researchers noted in their paper.

The researchers said that in the 10 years after delivery, relative rates of ischemic heart disease were increased twofold in women with other hypertensive disorders of pregnancy (46 extra cases per 100,000 person-years), 1.7-fold in those with preterm delivery (19 extra cases per 100,000), 1.5-fold in those with pre-eclampsia (12 extra cases per 100,000), 1.3-fold in those with gestational diabetes, and 1.1-fold in those who delivered a small for gestational age infant, after adjusting for all other factors.

Additionally, women who experienced more than one pregnancy complication showed further increases in risk in the ten years after delivery.

The researchers also found that the possibility of developing heart disease increased with the number of pregnancy complications.

The researchers wrote that while women who experienced one pregnancy complication were 1.3 times more likely to develop heart disease, those who experienced two or three complications were 1.8 and 2.3 times more likely, respectively.

Though most relative rates decreased over time, the risks were quite significant, ranging from 1.1 to 1.5 times even 30-46 years after delivery; and were only partially explained by shared genetic or environmental factors within families, they added.

“Women with adverse pregnancy outcomes should be considered for early preventive evaluation and long-term risk reduction to help prevent the development of ischemic heart disease,” they concluded.