(486) Establishing a mean arterial pressure threshold for severe hypertension in labor

Current definitions of severe hypertension in pregnancy rely on different systolic and diastolic thresholds, which may be inconsistently applied in non-obstetric clinical settings. Unlike these dual cutoffs, mean arterial pressure (MAP) offers a single, integrated value that could streamline recognition and triage. However, no validated MAP threshold currently exists. We sought to identify a MAP cutoff that reliably detects severe-range blood pressure to improve detection and response in obstetric care.

Study Design:

We conducted a retrospective cohort study of all deliveries across 7 hospitals from 2019–2024. Among 7,996,632 recorded blood pressures, 6,971,692 physiologic readings were analyzed after excluding extreme or missing values. Severe hypertension was defined per ACOG criteria. We used receiver operating characteristic (ROC) analysis and Youden’s Index to determine the optimal MAP threshold and assessed diagnostic performance across clinically relevant cutoffs.

Results:

Of the 6.97 million readings, 146,581 (2.1%) met criteria for severe hypertension. The optimal MAP threshold was 103.2 mmHg (AUC 0.981; sensitivity 94.7%; specificity 91.0%). For clinical use, a MAP ≥100 mmHg had sensitivity 98.1% and specificity 85.8%, missing only 1.9% of severe cases. A more conservative threshold of MAP ≥110 mmHg improved specificity (97.4%) but reduced sensitivity (79.1%). Mean MAP was 119 mmHg (SD 13.0) in severe cases vs 86.3 mmHg (SD 11.9) in non-severe cases (p< 0.001).

Conclusion:
A MAP threshold of ≥100 mmHg reliably detects severe-range hypertension and may simplify recognition across diverse clinical settings, particularly where non-obstetric providers may be less familiar with dual systolic/diastolic criteria requiring urgent treatment. Adoption of a single, memorable MAP cutoff could improve timely identification and treatment of severe hypertension in pregnancy