The Early Warning Scoring (EWS) surveillance system is used to identify deteriorating patients and enable appropriate staff to be called promptly. However, there is a lack of evidence that EWS surveillance systems lead to a reduction in severe morbidity.

To determine whether as EWS may have improved the detection of severe maternal morbidity or lessened the severity of illness among women with severe morbidity at a large tertiary maternity unit at Auckland City Hospital (ACH), New Zealand.

Admissions to intensive care, cardiothoracic and vascular intensive care, or an obstetric high‐dependency unit (HDU) were identified from clinical and hospital administrative databases. Case reviews and transcribed observation charts were presented to a multidisciplinary review group who, through group consensus, determined whether an EWS might have hastened recognition and/or escalation and effective treatment.

The multidisciplinary review team determined that an EWS might have reduced the seriousness of maternal morbidity in five cases (7.6%), including three admissions for obstetric sepsis to intensive care unit and two to obstetric HDU for post‐partum haemorrhage. No patient had a complete set of respiratory rate, heart rate, blood pressure and temperature recordings at every time period.

These findings have been used to support introduction of an EWS to the maternity unit at ACH.