Risk of cardiovascular disease following preeclampsia in twin pregnancies

Background Preeclampsia (PE) affects 4-5% of pregnancies and is associated with an increased risk of long-term cardiovascular disease. In twin pregnancies, the incidence of PE is 2-3 times higher. However, it remains unclear whether the long-term increased risk of cardiovascular disease also applies to twin pregnancies complicated by PE. Purpose To compare the long-term risk of cardiovascular disease in women with twin versus singleton pregnancies complicated by PE. Method Primiparous women who gave birth (1997-2018) were identified through Danish national registries and twin and singleton pregnancies with and without PE were compared. The primary outcome was postpartum hypertension and a composite of major adverse cardiovascular events (MACE, i.e., arrhythmia, heart failure, ischemic stroke, and acute myocardial infarction). Results The study population comprised 580,603 women, including 566,298 singleton and 14,305 twin pregnancies, of which 4.3% and 12.3%, respectively, were complicated by PE. The incidence rates of postpartum hypertension were 6.83 [95%CI 5.93-7.88] and 2.93 [%CI95 2.71-3.17] per 1,000 person-years (PY) among women with twin pregnancies with and without PE, respectively, and 9.10 [%95CI 8.80-9.41] and 2.36 [%95CI 2.33-2.40] per 1,000 PY among those with singleton pregnancies, with and without PE, respectively (cumulative incidences, Figure 1). In Cox regression analyses, the associated risk of postpartum hypertension was significantly higher among women with twins and PE compared with those with twins without PE (unadjusted HR 2.88 [%95CI 2.41-3.44]; adjusted HR 2.75 [%95CI 2.30-3.29]), and significantly lower compared with singleton pregnancies with PE (unadjusted HR 0.75 [%95CI 0.64-0.87]; adjusted HR 0.73 [%95CI 0.62-0.85]). The incidence rates of MACE were 1.99 [95% CI 1.54-2.55] and 1.87 [%CI95 1.70-2.05] per 1,000 PY among women with twin pregnancies with and without PE, respectively, and 2.35 [%95CI 2.21-2.50] and 1.54 [%95CI 1.51-1.56] per 1,000 PY among those with singleton pregnancies with and without PE, respectively (cumulative incidences, Figure 2). In Cox regression analyses, women with twin pregnancies and PE had a significantly increased, associated risk of MACE compared with those with twin pregnancies without PE (unadjusted HR 1.47 [%95CI 1.05-2.05]; adjusted HR 1.40 [%95CI 1.00-1.96]), but a similar, associated risk of MACE compared with women with singletons and PE (unadjusted HR 0.90 [%95CI 0.65-1.23]; adjusted HR 0.82 [%95CI 0.60-1.13]). Conclusion Preeclamptic women with twin pregnancies have an increased, associated risk of postpartum cardiovascular disease compared with women with twin pregnancies without PE. However, their associated risk of postpartum hypertension is lower than among preeclamptic women with singletons, while the associated risk of MACE is similar. These novel findings may help to individualise postpartum cardiovascular follow-up.Figure 1Figure 2