Table 1. The number and setting of eligible studies in each prediction model, and original population and setting for development of each study.

	Original patient population	Original setting	External Validation in another Obstetric population (number of studies)
Acute Physiology And Chronic Health Evaluation score II & III*	Non-obstetric	ICU	21
Simplified Acute Physiology Score 2 & 3	Non-obstetric	ICU	9
Sepsis-related Organ Failure Assessment	Non-obstetric	ICU	5
Mortality Prediction Model 2 & 3	Non-obstetric	ICU	3
World Health Organization criteria	Obstetric	ICU	1
Obstetric Early Warning Score	Obstetric	ICU	1
Collaborative Integrated Pregnancy High-dependency Estimate of Risk	Obstetric	ICU	0
Maternal Severity Index	Obstetric	General ward	2
Maternal Mortality Score	Obstetric	General ward **	0

ICU = intensive care unit

* include updated tool from original model

** Hospitals in developing countries