Obstetric early warning scores and escalation

It is 04:00 on the postnatal ward. The woman in bay 4 is restless, breathing 26 a minute, heart rate 118. The midwife has written the numbers on the chart and added a small note: "appears unwell". Every maternal death enquiry of the last two decades has the same opening paragraph: physiological deterioration was documented in the hours before collapse, and not acted upon. The early warning score exists to convert a written number into a summoned senior. This topic teaches you how to design, validate, defend and use one.^[6][10]

Overview and definition

A track-and-trigger system has two halves. Tracking means a structured set of observations, charted at a defined frequency, with abnormal values flagged by colour. Triggering means a defined response — usually a mandatory bedside review by a clinician within a set time — when a threshold is crossed. Either half without the other is decoration. The chart without the pathway is paper; the pathway without the chart is untraceable.^[6][11]

The obstetric version exists because the pregnant baseline is not the non-pregnant baseline. A heart rate of 95, a blood pressure of 95/55, a respiratory rate of 20 — each of these is normal late in pregnancy and would not flag on a general adult chart. The obstetric chart moves the goalposts so that the abnormality relative to the pregnant baseline is what triggers, not the abnormality relative to a non-pregnant reference. Get the baselines right, or the chart misses what it was built to catch.^[1][11]

References12ShowHide

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2. [2]Carle C, Alexander P, Columb M, Johal J Design and internal validation of an obstetric early warning score: secondary analysis of the Intensive Care National Audit and Research Centre Case Mix Programme database Anaesthesia, 2013.PMID 23488833
3. [3]Edwards SE, Grobman WA, Lappen JR, Winter C, Fox R, Lenguerrand E, Draycott T Modified obstetric early warning scoring systems (MOEWS): validating the diagnostic performance for severe sepsis in women with chorioamnionitis Am J Obstet Gynecol, 2015.PMID 25446705
4. [4]Shields LE, Wiesner S, Klein C, Pelletreau B, Hedriana HL Use of Maternal Early Warning Trigger tool reduces maternal morbidity Am J Obstet Gynecol, 2016.PMID 26924745
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7. [7]Smith V, Kenny LC, Sandall J, Devane D Physiological track-and-trigger/early warning systems for use in maternity care Cochrane Database Syst Rev, 2021.PMID 34515991
8. [8]Polprasarn P, Thongwon T Modified Early Obstetric Warning Criteria Predict Maternal Morbidity in the Immediate Postpartum Period: A Case-Control Study Nurs Womens Health, 2023.PMID 37837995
9. [9]Main EK, Fuller M, Kovacheva VP, Elkhateb R Performance Characteristics of Sepsis Screening Tools During Delivery Admissions Obstet Gynecol, 2024.PMID 38086055
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11. [11]Chu J, Johnston TA, Geoghegan J Maternal Collapse in Pregnancy and the Puerperium: Green-top Guideline No. 56 BJOG, 2020.PMID 31845507
12. [12]Foy KE, Pearson J, Kettley L, Lal N Four early warning scores predict mortality in emergency surgical patients at University Teaching Hospital, Lusaka: a prospective observational study Can J Anaesth, 2020.PMID 31598906