Hypertensive Disorders of Pregnancy and Pre-Pregnancy Hypertension with Subsequent Incident Venous Thromboembolic Events

Hypertensive disorders of pregnancy (HDP) and pre-pregnancy hypertension contribute to maternal morbidity and mortality. We examined the association of HDP and pre-pregnancy hypertension with subsequent venous thromboembolic (VTE) events. The retrospective cohort study included 444,859 women with ≥1 live, singleton birth in South Carolina (2004–2016). Hospital and emergency department visit and death certificate data defined incident VTE, HDP, and pre-pregnancy hypertension. Birth certificate data also defined the exposures. Adjusted Cox proportional hazards methods modeled VTE events risk. Of the cohort, 2.6% of women had pre-pregnancy hypertension, 5.8% had HDP, 2.8% had both pre-pregnancy hypertension and HDP (both conditions), and 88.8% had neither condition. The risk of incident VTE events within one year of delivery was higher in women with HDP (hazard ratio [HR] = 1.62, 95% confidence interval [CI]: 1.15–2.29) and both conditions (HR = 2.32, 95% CI: 1.60–3.35) compared to those with neither condition as was the risk within five years for women with HDP (HR = 1.35, 95% CI: 1.13–1.60) and for women with both conditions (HR = 1.82, 95% CI: 1.50–2.20). One- and five-year risks did not differ in women with pre-pregnancy hypertension compared to women with neither condition. Compared to non-Hispanic White (NHW) women with neither condition, the incident VTE event risk was elevated within five years of delivery for NHW (HR = 1.29, 95% CI: 1.02–1.63; HR = 1.59, 95% CI: 1.16–2.17) and non-Hispanic Black (NHB; HR = 1.51, 95% CI: 1.16–2.96; HR = 2.08, 95% CI: 1.62–2.66) women with HDP and with both conditions, respectively, and for NHB women with pre-pregnancy hypertension (HR = 1.50, 95% CI: 1.09–2.07). VTE event risk was highest in women with HDP, and the event rates were higher in NHB women than in NHW women in the same exposure group.