Cardiovascular mortality risk a decade after twin and singleton pregnancies complicated by hypertensive disorders of pregnancy

Objectives: To describe the cardiovascular mortality (CVM) risk in women after twin versus singleton pregnancies complicated by hypertensive disorders of pregnancy (HDP). Study design: Retrospective cohort study of nulliparous women with a twin or singleton pregnancy who delivered in the Netherlands between 1995 and 2015. We used data of the Perinatal Registry of the Netherlands and data of the National Death Registry to determine baseline data, the occurrence of HDP and CVM. In the two main analyses we compared twin pregnancies complicated by HDP to 1) singleton pregnancies complicated by HDP and 2) uncomplicated twin pregnancies (i.e. without HDP) of women who delivered within a hospital setting. Main outcome measures: CVM risk using cox-proportional hazard models, adjusted for maternal age (aHR). Results: 1,243,231 nulliparous women were included, of which 30,623 (2.5%) had a twin and 1,212,608 (97.5%) had a singleton pregnancy. A total of 9,853 (32.2%) twin pregnancies were complicated by HDP, versus 249,141 (20.6%) singleton pregnancies (p < 0.0001). Within the HDP twin cohort, 14/73 (19.2%) maternal deaths were due to cardiovascular causes, versus 335/1,788 (18.7%) in the HDP singleton cohort and 10/117 (8.6%) in the uncomplicated twin cohort. The corresponding aHR was 2.85 (95% CI 1.26–6.41; p = 0.01) for the HDP twin versus the uncomplicated twin cohort, and 1.05 (95% CI 0.62–1.80; p = 0.85) for the HDP twin versus the HDP singleton cohort. Conclusions: Women after both twin and singleton pregnancies complicated by HDP are at a similarly increased risk of CVM later in life.