Obstetric admissions to intensive care units in Australia and New Zealand: A registry‐based cohort study

OBJECTIVE: Describe the epidemiology of obstetric patients admitted to an Intensive Care Unit (ICU). DESIGN: Registry-based cohort study. SETTING: 183 ICU's in Australia and New Zealand. POPULATION: Women aged 15 to 49 years, admitted to ICU between 2008 and 2017, classified as pregnant, post-partum, or with an obstetric-related diagnosis. METHODS: Data was extracted from the Australia and New Zealand Intensive Care Society (ANZICS) Adult Patient Database, and national agencies. MAIN OUTCOME MEASURES: Incidence of ICU admission, cohort characteristics, maternal outcomes and changes over time. RESULTS: The cohort comprised 16,063 patients. The annual number of obstetric ICU admissions increased, while their proportion of total ICU admissions (1.3%) did not change (Odds Ratio 1.02; 95% CI, 0.99 - 1.04, P=0.14). There were 10,518 (65%) with an obstetric-related ICU diagnosis, and 5,545 (35%) with a non-obstetric ICU diagnosis. Mean (SD) age was 31 (6.4) years, 1,463 (9.1%) were Indigenous, 2,305 (14%) were transferred from another hospital, and 3,008 (19%) received mechanical ventilation. Median [IQR] length of stay in hospital was 5.2 [3.1 - 7.9] days, which included 1.1 [0.7 - 1.8] days in ICU. There were 108 (0.7%) maternal deaths, most (N=97, 90%) having a non-obstetric diagnosis. There was no change in risk-adjusted length of stay or mortality over time. CONCLUSIONS: Obstetric patients account for a stable proportion of ICU admissions in Australia and New Zealand. These patients typically have a short length of ICU stay and low hospital mortality.