Heart disease in pregnancy and risk of pre-eclampsia: a Swedish register-based study.

Background and aims: Pre-eclampsia complicates 3-5% of pregnancies worldwide and is associated with adverse outcomes for the mother and the offspring. Pre-eclampsia and heart failure have common risk factors, including hypertension, obesity and diabetes. It is not known whether heart failure increases the risk of pre-eclampsia. This study examines whether pregestational heart failure increases the risk of pre-eclampsia.

Methods: In a registry-based case-cohort study that included all pregnancies in Sweden (n=3 125 527) between 1990 and 2019, all pregnancies with pre-eclampsia (n=90 354) were identified and up to five control pregnancies (n=451 466) for each case were chosen, matched on the mother's birth year. Multiple logistic regression analysis was used to evaluate the impact of heart failure on the risk of pre-eclampsia, with adjustment for established risk factors and other cardiovascular diseases.

Results: Women with heart failure had no increased risk for pre-eclampsia, OR 1.02 (95% CI 0.69 to 1.50). Women with valvular heart disease had an increased OR of preterm pre-eclampsia, with an adjusted OR of 1.78 (95% CI 1.04 to 3.06). Hypertension and diabetes were independent risk factors for pre-eclampsia. Obesity, multifetal pregnancies, in vitro fertilisation, older age, Nordic origin and nulliparity were more common among women who developed pre-eclampsia compared with controls.

Conclusion: Women with heart failure do not have an increased risk of pre-eclampsia. However, women with valvular heart disease prior to pregnancy have an increased risk of developing preterm pre-eclampsia independent of other known risk factors.