(630) Undocumented obstetric hypertension is associated with severe maternal morbidity and unplanned postpartum hospital utilization

Obstetric hypertension (HTN) may not always be recognized and captured by ICD-10 diagnosis codes in the electronic medical record. However, we propose that even in the absence of an ICD-10 code for chronic hypertension (cHTN) or hypertensive disorders of pregnancy (HDP), patients with elevated blood pressure (BP) remain at increased risk of adverse peripartum outcomes. We aimed to compare (1) rates of severe maternal morbidity (SMM) at delivery and (2) rates of unplanned hospital utilization within 6 weeks postpartum (PP) amongst normotensive patients and those with undocumented/documented HTN.

Study Design:

This was a retrospective study of patients delivering within a single system from 2013-2024 with ≥1 prenatal visit and ≥2 recorded BPs. Patients were classified as “normotensive” (no HTN), “BP only” (≥2 BPs of ≥140/90 mmHg from 0-20 weeks’ gestation or 20 weeks-delivery discharge without an ICD-10 code for cHTN/ HDP), or “ICD-10” (with an ICD-10 code for cHTN/HDP). Demographic and clinical attributes were compared across groups using chi-square tests. The primary outcomes were SMM and ED visits or inpatient readmission within 6 weeks PP. These were compared using multivariate logistic regression, adjusted for significant covariates.

Results:

Of 59734 patients, 33229 (55.6%) were identified as normotensive, 11443 as BP only (19.2%), and 15062 (25.2%) as ICD-10 (Table 1). The ICD-10 group experienced the highest rates of SMM (8.1%, aOR 2.4 [95% CI 2.2-2.7]), PP ED visits (10.7%, 2.0 [1.9-2.2]), and readmissions (7.1%, 7.6 [6.6-8.7]) (Table 2). However, the BP only group was also at increased risk of adverse outcomes compared to the normotensive group, including SMM (3.9 vs 2.8%, aOR 1.4 [95% CI 1.3-1.6]) and PP ED visits (5.6 vs 4.8%, 1.2 [1.1-1.3]), although not readmissions [1.0 vs 0.9%, 1.2 [0.9-1.4]).

Conclusion:

Even in the absence of a formal diagnosis by ICD-10 coding, elevated peripartum BP is associated with SMM and PP hospital utilization. This further highlights the importance of appropriate recognition and documentation of antenatal HTN.