Major Adverse Pregnancy Outcome Associated With 2-Fold Increase in Relative Rate of Ischemic Heart Disease

Adverse pregnancy outcomes were associated with long-term risk of ischemic heart disease, which was only partially explained by familial factors, according to a new study published in BMJ. There were 5 major adverse pregnancy outcomes evaluated in the study—preterm delivery, small for gestational age, pre-eclampsia, other hypertensive disorders of pregnancy, and gestational diabetes.

“All major adverse pregnancy outcomes should be recognized as lifelong risk factors for ischemic heart disease,” the investigators wrote in the paper. “Co-sibling analyses suggested that these findings were only partially explained by shared genetic and environmental factors.”

Women with other hypertensive disorders of pregnancy had a 2-times higher relative rate of ischemic heart disease 10 years post-delivery. Relative rates of the disease remained significantly increased for 46 years post-pregnancy.

Adverse pregnancy outcomes are under-recognized cardiovascular risk factors, with an estimated 30% of women experiencing at least 1 during her reproductive years. Whether adverse pregnancy outcomes are a risk for cardiovascular disease or uncover a pre-existing risk remains a knowledge gap in the literature, which the current study aimed to address.

Investigators conducted a national cohort study of 2,195,266 women with a first singleton delivery in Sweden between 1973 and 2015. The study evaluated the link between the 5 major pregnancy outcomes and risk of ischemic heart disease over the course of a lifetime. Follow-up was 46 years for some patients.

The team hypothesized that adverse pregnancy outcomes increased the risk of ischemic heart disease, and the results appeared to confirm suspicions that each of the 5 adverse outcomes was independently associated with risk of ischemic heart disease.

Pre-eclampsia and gestational diabetes were associated with the highest rates of ischemic heart disease throughout the entire 46-year follow-up period. The number of pre-eclampsia cases 121.9 per 100,000 person years, and the number of patients with gestational diabetes who developed ischemic heart disease were 113.0 per 100,000 person years.

Adjusting for maternal factors and other adverse pregnancy outcomes, women with preterm delivery experienced a 1.7-fold increased relative rate of ischemic heart disease at 10 years post-delivery.

Those with pre-eclampsia experienced a 1.7-fold increase, patients with gestational diabetes had a 1.3-fold increase, and delivering a small for gestational age infant caused a 1.1-fold increased rate of ischemic heart disease.

Additionally, one-third (667,774 women) of all participants experienced an adverse pregnancy outcome. The most common adverse pregnancy outcomes were delivering an infant who was small for gestational age and preterm delivery. A combination of multiple adverse outcomes further increased the patient’s risk of heart disease.

Study limitations included a lack of detailed clinical records to verify diagnosed ischemic heart disease, underreported ischemic heart disease diagnoses, possible residual confounding, a lack of information on behavioral factors such as physical activity, and the data are limited to a Swedish population.

“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,” the study authors wrote.

Reference

Crump C, Sundquist J, McLaughlin M.A., et al. Adverse pregnancy outcomes and long term risk of ischemic heart disease in mothers: national cohort and co-sibling study. BMJ. 2023;380:e072112.