Pregnancy-associated mortality due to cardiovascular disease: Impact of hypertensive disorders of pregnancy

Abstract

Background: Reported rates of maternal mortality in the United States have been staggeringly high and increasing, and cardiovascular disease (CVD) is a chief contributor to such deaths. However, the impact of hypertensive disorders of pregnancy (HDP) on the short-term risk of cardiovascular death is not well understood.

Objectives: To evaluate the association between HDP (chronic hypertension, gestational hypertension, preeclampsia, eclampsia, and superimposed preeclampsia) and pregnancy-associated mortality rates (PMR) from all causes, CVD-related causes both at delivery and within 1 year following delivery.

Methods: We used the Nationwide Readmissions Database (2010-2018) to examine PMRs for females 15-54 years old. International Classification of Disease 9 and 10 diagnosis codes were used to identify pregnancy-associated deaths due to HDP and CVD. Discrete-time Cox proportional hazards regression models were used to calculate adjusted hazard ratios (HR) and 95% confidence intervals (CI) for mortality at delivery (0 days) and at <30, <60, <90, <180, and <365 days after delivery in relation to HDP.

Results: Of 33,417,736 hospital deliveries, the rate of HDP was 11.0% (n = 3,688,967), and the PMR from CVD was 6.4 per 100,000 delivery hospitalisations (n = 2141). Compared with normotensive patients, HRs for CVD-related PMRs increased with HDP severity, reaching over 58-fold for eclampsia patients. HRs were higher for stroke-related (1.2 to 170.9) than heart disease (HD)-related (0.99 to 39.8) mortality across all HDPs. Except for gestational hypertension, the increased risks of CVD mortality were evident at delivery and persisted 1 year postpartum for all HDPs.

Conclusions: HDPs are strong risk factors for pregnancy-associated mortality due to CVD at delivery and within 1 year postpartum; the risks are stronger for stroke than HD-related PMR. While absolute PMRs are low, this study supports the importance of extending postpartum care beyond the traditional 42-day postpartum visit for people whose pregnancies are complicated by hypertension.

Keywords: cardiovascular disease; heart disease; hypertensive disorders of pregnancy; pregnancy‐associated mortality; stroke.

Figure 1

Pregnancy-associated mortality rates from heart disease and stroke by hypertensive disorders of pregnancy, eclampsia (ECL), superimposed preeclampsia (SUP), preeclampsia with severe features (PES), chronic hypertension (CHR), preeclampsia without severe features (PEM), gestational hypertension (GHTN), and normotension (NORM) at delivery and after delivery: Nationwide Readmissions Database, 2010–2018

Figure 2

Prevalence rates of hypertensive disorders of pregnancy from 2010 to 2018 (panel A), and pregnancy-associated mortality rates from cardiovascular disease in relation to hypertensive disorders of pregnancy over time (panel B): Nationwide Readmissions Database, 2010–2018

Figure 3

Cumulative adjusted hazard ratios with 95% confidence interval of pregnancy-associated heart disease mortality rates from at delivery (0 days) and within <30, <60, <90, <180, and <365 days following delivery in relation to hypertensive disorders of pregnancy. Hazards ratios were adjusted for the confounding effects of assisted reproductive technology (ART) conception, pre-pregnancy diabetes, multiple gestation, maternal age, hospital bed size, hospital type, hospital teaching status income quartile, insurance, and year of delivery through a discrete-time Cox proportional hazards regression model: Nationwide Readmissions Database, 2010–2018

Figure 4

Cumulative adjusted hazard ratios with 95% confidence interval of pregnancy-associated stroke mortality rates at delivery (0 days) and within <30, <60, <90, <180, and <365 days following delivery in relation to hypertensive disorders of pregnancy: Nationwide Readmissions Database, 2010–2018 Hazards ratios were adjusted for the confounding effects of assisted reproductive technology (ART) conception, pre-pregnancy diabetes, multiple gestation, maternal age, hospital bed size, hospital type, hospital teaching status income quartile, insurance, and year of delivery through a discrete-time Cox proportional hazards regression model.