Prevalence of Persistent Severe Hypertension and Rates of Treatment Among Pregnant Patients in the Prehospital Setting

Hypertensive disorders of pregnancy (HDP) contribute to maternal and fetal morbidity and mortality and require time-sensitive intervention. In April 2025, the American College of Obstetricians and Gynecologists (ACOG), in collaboration with the National Association of EMS Physicians (NAEMSP) and the National Association of EMTs (NAEMT), published new guidelines on the prehospital management of elevated blood pressure in pregnancy. The objective of this study was to determine the prevalence of persistent severe hypertension among pregnant patients encountered by prehospital clinicians, characterize baseline frequency of pre-guideline treatment, and establish a benchmark to inform implementation of these guidelines. We conducted a retrospective observational cohort study using the 2024 ESO Data Collaborative public release research dataset (January 1 to December 31, 2024). We identified all 9-1-1 ground EMS scene responses for patients documented as pregnant beyond 20 weeks of gestation. We excluded injury-related encounters and patients outside the World Health Organization-defined childbearing age range (15 to 49 years). Consistent with the new guidelines, we defined persistent severe hypertension as at least two documented blood pressure measurements with systolic blood pressure ≥ 160 mmHg or diastolic blood pressure ≥ 110 mmHg. We defined guideline-adherent treatment as administration of both magnesium sulfate (MgSO4) and an antihypertensive medication (labetalol, hydralazine, or nifedipine). We identified 39,546 eligible 9-1-1 ground EMS scene responses for patients beyond 20 weeks of gestation. The prevalence of persistent severe hypertension was 3.1% (n = 1,234/39,546). Among these patients, 77 (6.2%) received magnesium sulfate only, 19 (1.5%) received an antihypertensive medication only, and 10 (0.8%) received guideline-adherent treatment with both magnesium sulfate and an antihypertensive medication. Approximately 1 in 32 pregnant patients beyond 20 weeks of gestation encountered by prehospital clinicians had persistent severe hypertension. In the year prior to dissemination of the 2025 ACOG, NAEMSP, and NAEMT-supported guidelines, fewer than 1% received guideline-adherent treatment with both magnesium sulfate and an antihypertensive medication. These findings establish a national benchmark and identify opportunities to improve prehospital care through protocol development, medication availability, clinician education, and implementation of updated guidelines.