Pregnant women who experience any pregnancy-related complications such as preterm delivery, pre-eclampsia are at high risk of developing heart disease as long as 46 years after child birth, according to a study from Sweden published in the BMJ.¹

Crump et al analysed data of Swedish women sourced from the Swedish Medical Birth Register between 1973 and 2015 who delivered a single live infant with the objective to study if adverse pregnancy outcomes had a link to the risk of ischemic heart disease, which was the main outcome measure. None of the selected study subjects had a history of heart disease. For the purpose of the study, they selected five outcomes namely preterm delivery (gestational age <37 completed weeks), preeclampsia, small for gestational age (infant birth weight <10th centile for gestational age), gestational diabetes and other hypertensive disorders of pregnancy. Small for gestational age was the commonest adverse pregnancy outcome in14.3% followed by preterm delivery  in ~9%. The part

Out of the 2,195,266 women included in the study, 667,774 (30.4%) women developed at least one adverse pregnancy outcome; 181,783 (8.3%) experienced at least two adverse pregnancy outcomes.

Nearly 4% or 83,881 women in the study group were diagnosed with ischemic heart disease such as acute myocardial infarction (AMI), angina (~38%) during the follow-up period of 46 years. An independent association was observed between all five adverse pregnancy outcomes and increased risk of ischemic heart disease.

After adjusting for variables like age, education, BMI, smoking, diabetes, high BP, high cholesterol levels and smoking, when the risk was assessed at 10 years after childbirth, compared with women who did not have a major adverse pregnancy outcome, those women who had had other hypertensive disorders of pregnancy such as chronic hypertension, gestational hypertension were twice as likely to develop ischemic heart disease with adjusted hazard ratio (aHR) of 2.09. The risk increased 1.5-fold among women with pre-eclampsia, 1.7-fold in women with preterm delivery, 1.1-fold in those who delivered a small-for-gestational age infant and 1.3 fold in those with gestational diabetes.

This high risk was seen to persist even when examined four decades (30-46 years) after delivery. The aHR for other hypertensive disorders of pregnancy was 1.47; for pre-eclampsia, the aHR was 1.32; for preterm delivery, the aHR was 1.23 and for gestational diabetes, it was 1.16. “These findings were only partially (<45%) explained by shared familial (genetic or environmental) factors in co-sibling analyses”, note the authors.

The risk was found to increase as the number of adverse pregnancy outcomes increased. Those who had experienced more than one adverse pregnancy outcome were at a higher risk of IHD. The risk of IHD within 10 years of childbirth increased 1.2-fold among women with one adverse outcome with aHR of 1.29. The risk was 1.8-fold higher among women who experienced 2 adverse outcomes with aHR of 1.80, while the risk rose 2.3 folds among those who had experienced three adverse pregnancy outcomes with aHR of 2.26.

Heart disease is a major cause of death among women. Besides chest pain, most symptoms of heart attack in women are often different from those classically associated with heart attack such as shortness of breath, nausea/vomiting and back or jaw pain and run the risk of being ignored.

This study points out the high risk of future heart disease among women who had experienced at least one adverse pregnancy outcome allowing identification of at-risk women.

Being an observational study, it does not conclusively prove the association. Nonetheless, interventions for risk modification of cardiovascular risk factors such as obesity, diabetes, hypertension, smoking should be initiated aggressively at the earliest to prevent heart disease in women who have a history of pregnancy-related complications. A close follow-up is imperative for better outcomes.

Reference

1. Crump C, et al. Adverse pregnancy outcomes and long term risk of ischemic heart disease in mothers: national cohort and co-sibling study. BMJ. 2023 Feb 1;380:e072112. doi: 10.1136/bmj-2022-072112.