Background: Despite having the highest health care spending, the US continues to have rates of maternal mortality over three times greater than similarly high-income countries. Generally, deaths occur in the days immediately following birth, and typically occur in hospital intensive care units (ICUs). As ICU utilization is often employed to identify indication of severe maternal morbidity, we sought to examine risk factors for in-hospital mortality from 2016 to 2023 among those with obstetric related indications and ICU admissions.

Methods: The Vizient® Clinical Data Base was queried for ICD-10-CM codes for those with diagnoses related to pregnancy, childbirth, and the puerperium (O00-O9A), and then further limited to a retrospective cohort of 43,337 persons aged 12-55 with admissions to ICUs (cardiac, medical, surgical, and combinations) discharged between 01/2016-06/2023 amongst 352 continuously reporting hospitals.

Results: Among those who had ICU admissions and had an obstetric indication, patients were 30±7 years, white (42%) or Black (37%), 15% were Hispanic, and the majority utilized Medicaid (54%) or commercial/private payer (36%). Patients were largely admitted in the South (42%) followed by the Midwest (30%). Most prevalent comorbidities included deficiency anemias (25%), obesity (24%), coagulopathy (21%), hypertension (20%), and diabetes (16%). Most common principal diagnoses included hypertensive disorders (e.g., pre-eclampsia), infections/viral diseases complicating pregnancy/childbirth, circulatory complications (e.g., cardiac arrhythmia in childbirth, cardiomyopathy), and puerperal sepsis. 774 (2%) patients died in hospital. Utilizing multivariable models, older age (OR:1.2, 95% CI: 1.0-1.2), Medicaid usage (OR:1.3, 95% CI: 1.1-1.5), and Southern region (OR: 1.1, 95% CI: 0.9-1.4) were strongly associated with risk for in-hospital mortality. Comorbidities that were significant risk factors for in-hospital mortality included metastatic cancer (OR: 14.4, 95% CI: 9.4-22.1), cerebrovascular disease (OR: 4.5, 95% CI: 3.6-5.0), coagulopathy (OR: 3.1, 95% CI: 2.6-3.6), and liver disease (OR: 3.0, 95% CI: 2.0-4.4). Rates of in-hospital mortality by quarter ranged from 1.1% to 3.1%, with statistically significant (p >0.05) increases beginning 2020 Q3 (1.7%), spiking in 2021 Q4 (3.1%), and slowly tapering thereafter (1.8% in 2023 Q2), among those with ICU admissions and obstetric indications. The most common principal diagnoses during trend spikes were overwhelmingly related to infections/viral diseases.

Conclusions: Examination of risk factors for in-hospital mortality, such as underlying comorbidities and social determinants of health, provides insights into obstetric health care policy and potential interventions. In line with other studies, an overall 2% of patients with ICU admissions and obstetric indications died in the hospital, notably increasing beginning with the COVID pandemic, and remaining at higher rates into 2023 compared to pre-pandemic. Increasing trends of in-hospital mortality are likely impacted by COVID infection and policies, as well as previously identified risk factors for severe maternal morbidity such as prenatal care inadequacy and upticks in C-sections.