69 - Association Between Hypertension Disorders of Pregnancy and Severe Maternal Morbidity

Publication Number: 2066.69

Marion E. Granger Howard, University of South Carolina, Marietta, GA, United States; Nansi Boghossian, University of South Carolina, Columbia, SC, United States; Berry Campbell, Univ of SC School of Medicine/Prisma Health, Columbia, SC, United States

Background: Hypertensive disorders of pregnancy (HDPs) and severe maternal morbidity (SMM) have both been associated with adverse infant outcomes. However, limited research has examined how specific HDPs are individually associated with SMM.

Objective: To examine the association between individual hypertensive disorders and SMM.

Design/Methods: We conducted a retrospective analysis using hospital administrative data from pregnancies resulting in live births or stillbirths at ≥20 weeks' gestation delivered at Prisma Health Midlands and Upstate facilities in South Carolina between 2016 and 2024 (n=98,202). Pregnancies ending in miscarriage or termination, and missing information on hypertensive disorders, were excluded. We compared individuals without hypertensive disorders to those with: chronic hypertension with superimposed pre-eclampsia (severe/mild or moderate/unspecified), chronic hypertension without superimposed pre-eclampsia, pre-eclampsia (severe/mild or moderate/unspecified), or gestational hypertension. We used Modified Poisson regression to estimate risks ratios (RR) and 95% CI for the association between each hypertensive disorder and SMM. The primary adjusted model included maternal race/ethnicity, parity, smoking, marital status, insurance, plurality, and preexisting diabetes mellitus. A secondary model further adjusted for a obstetric comorbidity index score (in place of plurality and diabetes).

Results: Hypertensive disorders were more prevalent among individuals who were non-Hispanic Black, aged ≥35 years, obese, unmarried, smokers, or publicly insured. Non-chronic hypertensive disorders were more common among nulliparous individuals and those < 20 years old, whereas chronic conditions predominated among multiparous individuals. All hypertensive disorders were associated with higher rates of cesarean delivery and delivery between 28-38 weeks' gestation. Deliveries at 20-27 weeks were most frequent among those with chronic hypertension or severe pre-eclampsia (Table 1). Each hypertensive disorder was associated with increased SMM risk. Adjusted RRs ranged from 1.74 (95% CI: 1.55-1.94) to 7.99 (95% CI: 6.82-9.36). Models adjusted for the comorbidity index yielded adjusted RRs from 1.57 (95% CI: 1.40-1.76) to 3.67 (95% CI: 3.29-4.08) (Table 2).

Conclusion(s): All hypertensive disorders of pregnancy were associated with increased SMM risk, regardless of severity. However, the magnitude of risk varied by condition, underscoring the importance of distinguishing between hypertensive disorder subtypes in clinical care.

Table 1. Sociodemographic Characteristics in the Full Sample and Among Birthing Individuals with each Hypertensive Disorder of Pregnancy
Data missing for: race/ethnicity n = 1,278 (1.3%); parity n = 610 (0.6%); smoking status n = 1,171 (1.2%); delivery BMI n = 41,311 (42.1%); delivery method n = 955 (1.0%); marital status n = 2,480 (2.5%); and insurance n = 73 (0.1%).

Table 2. Risk Ratios and 95% Confidence Intervals for the Association Between Hypertensive Disorders of Pregnancy and SMM
SMM was defined as a composite of the 20 indicators listed by the Centers for Disease Control, as well as blood transfusions of ≥1200 mL.
Adjusted models included maternal race/ethnicity, parity, smoking, marital status, insurance, plurality, and preexisting diabetes mellitus.
Adjusted + comorbidity index models adjusted for race/ethnicity, parity, smoking, marital status, insurance, and comorbidity index score.