Maternal cardiovascular risk after hypertensive disorder of pregnancy

Background and objective: Hypertensive disorders of pregnancy (HDPs) affect 5%-10% of pregnancies and have been associated with excess maternal cardiovascular disease (CVD) risk. The primary aim of this study was to reliably estimate absolute and relative risks of CVD after HDP.

Methods: A retrospective cohort of women who had singleton pregnancies in New South Wales, Australia, between 2002 and 2016 and identified using linked population health administrative databases. The primary exposure was new-onset HDP (pre-eclampsia/eclampsia and gestational hypertension), and the endpoint was hospitalisation or death due to ischaemic or hypertensive heart disease, or stroke. Kaplan-Meier analysis estimated risks among mothers following their first birth, and multivariable time-dependent Cox regression estimated the association between HDP and CVD.

Results: Among 528 106 women, 10.3% experienced HDP in their first pregnancy. The 10-year estimated risk of CVD was 2.1 per 1000 if no HDP and 5.5 per 1000 following HDP. Adjusting for demographics, gestational diabetes, small for gestational age and preterm birth, we found that there was an interaction between smoking and HDP, and a larger effect of early-onset (<34 weeks) HDP, compared with late-onset HDP. The HR for women with early-onset HDP who did not smoke was 4.90 (95% CI 3.00 to 7.80) and the HR for those who did smoke was 23.5 (95% CI 13.5 to 40.5), each compared with women without HDP who did not smoke.

Conclusion: In this nationally representative Australian cohort, HDP, especially early onset, conferred a clear increase in the risk of CVD, with amplification by smoking. Targeted preventive health, during and after pregnancy, could prevent a substantial burden of CVD among childbearing women.