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.
- smoking cessation
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CA and MN are joint first authors.
Contributors All authors were involved in the design of the study. MN carried out the statistical analyses. CA and MW wrote the first complete draft of the paper. All other authors contributed to further drafts and approved the final manuscript. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.
Funding MW is supported by the National Health and Medical Research Council of Australia (grant numbers 1080206 and 1149987). AH is supported by a National Health and Medical Research Council (Australia) Early Career Fellowship (1141570).
Competing interests MW has received consulting fees from Amgen, Inc, and Kyowa Kirin Co, Ltd.
Patient and public involvement Patients and/or the public were not involved in the design, conduct, reporting or dissemination plans of this research.
Patient consent for publication Not required.
Ethics approval Ethics approval was obtained from the NSW Population and Health Services Research Ethics Committee (reference number: 2018HRE0902). The study was conducted in accordance with the principles of the Declaration of Helsinki.
Provenance and peer review Not commissioned; internally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information. No additional data are available.