Abstract
Background
Early physiologic warning scores (EPWS) are used to detect clinical deterioration by monitoring vital signs and early warning signs. However, their role in the obstetric population, particularly during the preoperative period before cesarean delivery, remains underexplored.
Objective
To evaluate the effectiveness of three maternal early physiologic warning systems—Modified Early Obstetric Warning Score (MEOWS), Maternal Early Warning Criteria (MEWC), and Maternal Early Warning Triggers (MEWT)—in predicting short-term maternal and neonatal outcomes in the parturient patients undergoing cesarean section.
Methods
In this prospective observational study, 304 parturient patients scheduled for cesarean delivery at a tertiary care hospital were evaluated. Preoperative physiological data were used to calculate MEOWS, MEWC, and MEWT scores. Patients were classified into “high risk” (Group 1) or “no risk” (Group 2) categories based on predefined thresholds. Primary outcomes included intensive care unit (ICU) admission and neonatal APGAR scores. Secondary outcomes involved Aldrete scores, intraoperative hemodynamic parameters, and type of anesthesia.
Results
Patients identified as “high risk” by MEOWS had significantly lower neonatal APGAR and maternal Aldrete scores, along with higher systolic and diastolic blood pressures and heart rates (p < 0.05). MEOWS also more effectively predicted ICU admission compared to MEWC and MEWT (p < 0.05). No maternal deaths were recorded. Emergency procedures were more frequent in patients identified as “high risk” by MEWC and MEWT.
Conclusions
MEOWS, MEWC, and MEWT scores can help identify preoperative high-risk patients who may require cesarean sections. MEOWS demonstrated superior sensitivity in predicting postoperative complications and ICU admission. Incorporating EPWS in the preoperative evaluation may improve maternal and neonatal outcomes.
Keywords: Early physiologic warning scores, MEOWS, MEWC, MEWT, Maternal morbidity, Parturient
Introduction
Maternal morbidity and mortality remain critical global health challenges despite improvements in medical technology and perinatal care. According to the World Health Organization (2023), a woman dies every two minutes due to complications related to pregnancy or childbirth. Many of these deaths are preventable and often linked to delays in recognizing clinical deterioration [1–3].
Early physiologic warning scores (EPWS) have been developed to facilitate the early detection of clinical decline through easily measurable physiological parameters [4]. Originally designed for the general inpatient unit, EPWS have since been adapted for specific populations, including obstetric patients. In particular, systems such as Modified Early Obstetric Warning Score (MEOWS), Maternal Early Warning Criteria (MEWC), and Maternal Early Warning Triggers (MEWT) have been proposed to enhance surveillance and support timely clinical intervention in this group [5–8].
Pregnancy induces significant physiological changes that may mask early signs of critical illness. Therefore, using general EPWS without obstetric-specific modifications may lead to inaccurate risk assessment. While some studies have evaluated these systems in postpartum or critically ill obstetric patients, evidence remains limited regarding their predictive value in the preoperative cesarean context [9, 10].
This study aims to assess the effectiveness of MEOWS, MEWC, and MEWT scoring systems in predicting adverse maternal and neonatal outcomes before cesarean section. By identifying high-risk patients before surgery, we aimed to improve intraoperative preparedness, optimize resource allocation, and reduce preventable complications.
Patients and methods
Study design and ethical approval
This prospective observational cohort study was conducted at Süleyman Demirel University Faculty of Medicine between April 2022 and April 2023. The study protocol was approved by the university’s Institutional Review Board (IRB No: 2022-04/61) and registered with ClinicalTrials.gov (NCT06488690). Written informed consent was obtained from all participants before enrollment. The study adhered to the ethical principles outlined in the Declaration of Helsinki (2013).
Study population
Three hundred and four parturient patients scheduled for elective or emergency cesarean section were enrolled. Inclusion criteria encompassed patients aged 18–45 years with single or multiple viable pregnancies beyond 34 weeks of gestation. Exclusion criteria were recent surgeries within the last 72 h, chronic renal or hepatic failure, or refusal to participate.
Scoring systems and risk stratification
Three maternal early physiologic warning systems were assessed preoperatively:
MEOWS (Modified Early Obstetric Warning Score).
MEWC (Maternal Early Warning Criteria).
MEWT (Maternal Early Warning Triggers).
Each system evaluates a series of physiological parameters, including respiratory rate, blood pressure, oxygen saturation, pulse rate, and level of consciousness. Risk thresholds were defined based on standard system guidelines (summarized in Table 1).
Table 1.
Parameters and thresholds in maternal early physiologic warning systems
| MEOWS | MEWC | MEWT | |
|---|---|---|---|
| Respiratory rate (breaths/min) |
Red: <10 or > 30 Yellow: 21–30 |
< 10 or > 30 |
Red: >30 Yellow: 25–30 or < 12 |
| Oxygen saturation (%) | Red: <95 | < 95 |
Red: <90 Yellow: 90–93 |
| Temperature (°C) |
Red: <35 or > 38 Yellow: 35–36 |
Red:≥38 Yellow: ≤36 |
|
| Systolic blood pressure (mmHg) |
Red: <90 or > 160 Yellow: 150–160 or 90–100 |
< 90 or > 160 |
Red: >160 Yellow: 156–160 or > 80 |
| Diastolic blood pressure (mmHg) |
Red: >100 Yellow: 90–100 |
> 100 |
Red: >110 Yellow: 106–110 or < 45 |
| Mean arterial pressure (mmHg) | Red: <55 | ||
| Heart rate (beats/min) |
Red: <40 or > 120 Yellow: 40–50 or 100–120 |
< 50 or > 120 |
Red: >130 Yellow: 111–130 or < 50 |
| Pain score | Yellow: 2–3 | ||
| Neurological response |
Red: Responsive only to pain or unresponsive Yellow: Responsive to voice |
Maternal agitation, confusion, or unresponsiveness; patient with preeclampsia has persistent headache or shortness of breath |
Yellow: Impaired mental status |
| Urine output (mL/h for ≥ 2 h) | < 35 | - |
MEOWS Maternal Early Obstetric Warning Score, MEWC Maternal Early Warning Score, MEWT Maternal Early Warning Triggers
Patients were categorized into two groups for each scoring system:
Group 1 (Risk-positive): Triggered the EPWS alert.
Group 2 (Risk-negative): Did not trigger the alert.
Data collection
Demographic data, comorbidities, gestational age, and cesarean indications were recorded. Preoperative vital signs were used to calculate the scores. Postoperative variables included:
Neonatal APGAR scores at 1 and 5 min.
Maternal Aldrete Recovery Scores.
Type and duration of anesthesia.
Intensive care unit (ICU) admission status.
Surgical approach (elective vs. emergency).
Outcome measures
Primary outcome: ICU admission.
Secondary outcomes: Low APGAR score (< 7), low Aldrete score (< 9), emergency surgery, and abnormal vital signs.
Statistical analysis
Statistical analyses were conducted using SPSS version 23.0 (SPSS Inc., Chicago, IL, USA). Normality was assessed using the Kolmogorov-Smirnov test. Continuous variables were expressed as mean ± SD or median (IQR), as appropriate. Intergroup comparisons were conducted using Student’s t-test or Mann-Whitney U test for continuous variables, and chi-square test for categorical variables. A p-value < 0.05 was considered statistically significant.
Results
Patient characteristics
Among the 304 parturients included, the mean maternal age was 29.8 ± 6.2 years. Comorbidities were identified in 147 patients (48.4%), including diabetes mellitus (n = 33) and hypertension (n = 16) (Table 2). Gestational age was significantly lower in Group 1 compared to Group 2 across all three scoring systems (p < 0.05) (Table 2).
Table 2.
Demographic data
| MEOWS | MEWC | MEWT | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Severe (n = 85) | Mild (n = 219) | p | Severe (n = 39) | Mild (n = 265) | p | Severe (n = 38) | Mild (n = 266) | Severe (n = 85) | |
| BMI | 31.7 ± 5.8 | 30.1 ± 4.7 | 0.13 | 31.5 ± 5.9 | 30.4 ± 4.9 | 0.21 | 32.6 ± 6.0 | 30.2 ± 4.8 | < 0.01 |
| Age | 29.4 ± 6.5 | 30.2 ± 6.0 | 0.30 | 30.2 ± 6.7 | 29.9 ± 6.0 | 0.76 | 30.2 ± 6.3 | 29.9 ± 6.1 | 0.76 |
| Pregnancy week | 36.2 ± 2.6 | 37.0 ± 1.9 | < 0.01 | 35.8 ± 3.2 | 36.9 ± 2.0 | < 0.01 | 36.0 ± 3.2 | 36.9 ± 2.0 | < 0.05 |
| Number of pregnancies | 2.1 ± 1.4 | 2.3 ± 1.3 | 0.19 | 2.5 ± 1.7 | 2.2 ± 1.3 | 0.21 | 2.3 ± 1.7 | 2.3 ± 1.3 | 0.76 |
| Hypertension | 8 (9.4%) | 8 (3.7%) | 0.08 | 4 (10.3%) | 12 (4.5%) | 0.13 | 4 (10.5%) | 12 (4.5%) | 0.12 |
| Diabetes mellitus | 11 (12.9%) | 22 (10.0%) | 0.53 | 5 (12.8%) | 28 (10.6%) | 0.59 | 7 (18.4%) | 26 (9.8%) | 0.15 |
| Preeclampsia | 3 (3.5%) | 3 (1.4%) | 0.35 | 3 (7.7%) | 3 (1.1%) | < 0.05 | 3 (7.9%) | 3 (1.1%) | < 0.05 |
| Eclampsia | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | |||
| HELLP syndrome | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | |||
| Additional diseases | 48 (56.4%) | 99 (45.2%) | 0.09 | 20 (51.3%) | 127 (47.9%) | 0.73 | 24 (63.2%) | 123 (46.2%) | 0.06 |
Values are presented as mean ± SD. Significant p values are written in bold
MEOWS Maternal Early Obstetric Warning Score, MEWC Maternal Early Warning Score, MEWT Maternal Early Warning Triggers
Neonatal outcomes
As seen in Table 3, in the MEOWS-assessed group, both 1th- and 5th-minute APGAR scores were significantly lower in Group 1 than in Group 2 (p < 0.01). A similar pattern was observed for the maternal Aldrete score (p < 0.01). Although significant differences were also observed in the MEWC and MEWT groups (p < 0.05), the magnitude of these differences was less pronounced compared to the MEOWS group.
Table 3.
APGAR and aldrete scores
| MEOWS | MEWC | MEWT | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Severe (n = 85) | Mild (n = 219) | p | Severe (n = 39) | Mild (n = 265) | p | Severe (n = 38) | Mild (n = 266) | p | |
| APGAR score @ 1 st min. | 6.2 ± 1.8 | 7.0 ± 1.3 | < 0.01 | 6.6 ± 1.6 | 6.8 ± 1.4 | 0.39 | 6.5 ± 1.7 | 6.8 ± 1.4 | 0.22 |
| APGAR score @ 5th min. | 8.0 ± 1.9 | 8.6 ± 1.3 | < 0.01 | 8.0 ± 1.8 | 8.5 ± 1.4 | 0.06 | 7.8 ± 1.8 | 8.5 ± 1.4 | < 0.05 |
| Aldrete score | 8.7 ± 1.8 | 9.4 ± 0.7 | < 0.01 | 8.9 ± 1.5 | 9.3 ± 1.1 | 0.05 | 8.8 ± 1.5 | 9.3 ± 1.1 | < 0.05 |
Values are presented as mean ± SD. Significant p values are written in bold
MEOWS Maternal Early Obstetric Warning Score, MEWC Maternal Early Warning Score, MEWT Maternal Early Warning Triggers
Vital signs and risk parameters
Table 4 demonstrates that Group 1 parturients exhibited significantly elevated heart rate, systolic blood pressure, and respiratory rate in the MEOWS and MEWT assessments. Oxygen saturation and Glasgow Coma Scale scores were significantly lower in Group 1 within the MEOWS group (p < 0.01).
Table 4.
Physiological parameters
| MEOWS | MEWC | MEWT | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Severe (n = 85) | Mild (n = 219) | p | Severe (n = 39) | Mild (n = 265) | p | Severe (n = 38) | Mild (n = 266) | p | |
| Respiratory rate (breaths/min) | 20.1 ± 5.2 | 16.3 ± 3.3 | < 0.01 | 18.8 ± 5.8 | 17.1 ± 4.0 | < 0.05 | 19.1 ± 5.6 | 17.1 ± 4.0 | < 0.01 |
| Oxygen saturation (%) | 97.2 ± 1.9 | 98.0 ± 1.4 | < 0.01 | 97.2 ± 2.0 | 97.9 ± 1.5 | < 0.05 | 97.5 ± 1.8 | 97.8 ± 1.5 | 0.29 |
| Temperature (°C) | 36.4 ± 0.3 | 36.3 ± 0.2 | < 0.05 | 36.4 ± 0.3 | 36.3 ± 0.2 | 0.09 | 36.5 ± 0.3 | 36.3 ± 0.2 | < 0.01 |
| Systolic blood pressure (mmHg) | 134.7 ± 23.0 | 125.3 ± 12.8 | < 0.01 | 141.2 ± 27.7 | 126.0 ± 13.5 | < 0.01 | 139.1 ± 29.3 | 126.3 ± 13.5 | < 0.01 |
| Diastolic blood pressure (mmHg) | 78.5 ± 13.4 | 73.1 ± 10.4 | < 0.01 | 78.8 ± 15.3 | 74.0 ± 10.8 | < 0.05 | 77.9 ± 15.8 | 74.2 ± 10.8 | 0,06 |
| Heart rate (beats/min) | 108.2 ± 15.3 | 90.6 ± 12.7 | < 0.01 | 112.6 ± 19.2 | 93.0 ± 13.2 | < 0.01 | 115.1 ± 17.3 | 92.7 ± 13.2 | < 0.01 |
| Glasgow Coma Scale score | 14.5 ± 2.2 | 15.0 ± 0.0 | < 0.01 | 14.6 ± 1.9 | 14.9 ± 1.0 | 0.28 | 14.6 ± 1.9 | 14.9 ± 1.0 | 0.27 |
Values are presented as mean ± SD. Significant p values are written in bold
MEOWS Maternal Early Obstetric Warning Score, MEWC Maternal Early Warning Score, MEWT Maternal Early Warning Triggers.
ICU admission and surgical profile
All four postoperative ICU admissions occurred in Group 1 based on MEOWS assessment (p < 0.05), while no significant ICU admissions were associated with MEWC or MEWT classifications (Table 4). Emergency cesarean sections were significantly more common in high-risk groups in both MEWC and MEWT systems (p < 0.05), but not for MEOWS (Table 5).
Table 5.
Operative and anesthetic characteristics
| MEOWS | MEWC | MEWT | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Severe (n = 85) | Mild (n = 219) | p | Severe (n = 39) | Mild (n = 265) | p | Severe (n = 38) | Mild (n = 266) | p | |
| Operation type | |||||||||
| Emergency | 28 (32.9%) | 49 (22.4%) | 0.07 | 18 (46.2%) | 59 (22.3%) | < 0.05 | 16 (42.1%) | 61 (22.9%) | < 0.05 |
| Elective | 57 (67.1%) | 170 (77.6%) | 0.07 | 21 (53.8%) | 206 (77.7%) | < 0.05 | 22 (57.9%) | 205 (77.1%) | < 0.05 |
| Anesthesia type | |||||||||
| General | 38 (44.7%) | 68 (31.1%) | < 0.05 | 16 (41.0.0%) | 90 (34.0.0%) | 0.47 | 14 (36.8%) | 92 (34.6%) | 0.86 |
| Regional | 47 (55.3%) | 151 (69.0.0%) | < 0.05 | 23 (59.0.0%) | 175 (66.0.0%) | 0.47 | 24 (63.2%) | 174 (65.4%) | 0.86 |
| Anesthesia duration (min) | 87.2 ± 31.3 | 86.8 ± 21.3 | 0.89 | 91.5 ± 25.6 | 86.2 ± 24.3 | 0.21 | 86.7 ± 26.2 | 86.9 ± 24.2 | 0.95 |
| Operative time (min) | 82.4 ± 59.5 | 75.0 ± 20.1 | 0.10 | 79.1 ± 23.2 | 76.7 ± 37.3 | 0.70 | 75.7 ± 23.6 | 77.2 ± 37.3 | 0.81 |
| Hospital stay (days) | 2.8 ± 1.8 | 2.4 ± 1.9 | 0.11 | 2.3 ± 1.3 | 2.5 ± 1.9 | 0.43 | 2.5 ± 1.5 | 2.5 ± 1.9 | 0.91 |
| Discharge to ward | 81 (95.3%) | 219 (100%) | < 0.05 | 38 (97.4%) | 262 (98.9%) | 0.42 | 37 (97.4%) | 263 (98.9%) | 0.41 |
| ICU transfer | 4 (4.7%) | 0 (0.0%) | < 0.05 | 1 (2.6%) | 3 (1.1%) | 0.42 | 1 (2.6%) | 3 (1.1%) | 0.41 |
Values are presented as mean ± SD. Significant p values are written in bold
MEOWS Maternal Early Obstetric Warning Score, MEWC Maternal Early Warning Score, MEWT Maternal Early Warning Triggers
Anesthesia and operative variables
As seen in Table 5, no significant differences were observed between Groups 1 and 2 in terms of anesthesia duration, operative time, or length of hospital stay. However, general anesthesia was more frequently administered in high-risk MEOWS patients (p < 0.05), whereas no such difference was noted for MEWC or MEWT groups.
Discussion
This prospective study evaluated the predictive performance of three maternal early physiologic warning scoring systems (MEOWS, MEWC, and MEWT) applied during the preoperative assessment of parturient for cesarean section. The findings suggest that these systems, particularly MEOWS, can effectively identify high-risk obstetric patients and predict adverse maternal and neonatal outcomes [11, 12].
The MEOWS system was significantly associated with key negative outcomes such as lower neonatal APGAR scores, reduced maternal Aldrete scores, elevated heart rate and blood pressure, and ICU admissions. These results align with previous literature indicating that MEOWS is a reliable early indicator of physiological deterioration in obstetric populations, thereby supporting timely clinical interventions to reduce maternal morbidity [13–15]. Early identification through MEOWS significantly reduces the time to escalation of care [13]. Austin et al. also reported improvements in maternal outcomes following the routine implementation of MEOWS [15].
Interestingly, while all three systems are based on similar observed physiological parameters, their predictive accuracy varied. MEWC and MEWT were less sensitive in detecting ICU admission and postoperative complications. This could be attributed to differences in scoring thresholds and the definition of risk trigger points [16]. In our study, MEOWS was the only system to classify all ICU-admitted patients as “high risk” (Group 1), suggesting its potential superiority in the preoperative setting. While MEWC remains useful in certain intrapartum contexts, its lower sensitivity compared to MEOWS has been noted in earlier studies [16].
Despite the absence of maternal deaths in our cohort, the study still provides valuable insight. The lack of mortality may reflect the relatively young age of patients, early surgical intervention, or the overall high quality of antenatal and peripartum care at our institution [17, 18]. Additionally, the institutional emphasis on the use of early physiologic warning protocols may have contributed to the favorable outcomes observed.
The ability of MEOWS to predict ICU transfer even in a low-mortality population highlights its clinical utility. Early identification of high-risk patients not only optimizes maternal care but also allows for advanced neonatal preparedness, which is crucial given the strong association between maternal instability and neonatal morbidity [19].
Our results also suggest a correlation between higher EPWS and an increased rate of emergency cesarean deliveries, especially in the MEWC and MEWT groups. This aligns with the notion that physiologically unstable patients are more likely to undergo urgent interventions [20]. However, the difference was not statistically significant in the MEOWS group, potentially due to the smaller proportion of emergency cases within that subgroup. Further large-scale studies are warranted to clarify this relationship.
This study addresses an underexplored niche—the preoperative phase—where implementation of EPWS can influence anesthetic planning, resource allocation, and surgical preparation. Prior research has mostly focused on postpartum scoring, critical care outcomes, or retrospective validation [21]. By contrast, our approach promotes proactive perioperative surveillance and supports the integration of EPWS into pre-anesthetic assessments. Future research should explore whether tailored EPWS modifications specific to the preoperative obstetric population could further enhance predictive accuracy.
Limitations
Our study had several limitations. First, it was conducted at a single tertiary center, which may limit generalizability. Second, the number of ICU admissions was low (n = 4), and no maternal deaths occurred, limiting conclusions regarding mortality. Third, the physiologic scoring systems were applied only once in the preoperative period; serial assessments throughout the perioperative course may yield more dynamic insights. Finally, severe pregnancy complications such as HELLP syndrome and eclampsia were rare in our cohort.
Future directions
Further multi-center studies with larger sample sizes and extended follow-up are warranted to validate our findings, explore the cost-effectiveness of routine EPWS implementation, and examine the potential for integrating scoring systems into clinical decision-support tools in obstetric anesthesia.
Conclusion
This study demonstrates that maternal early physiologic warning scoring systems—particularly MEOWS—are effective for identifying parturient patients at high risk of perioperative complications prior to cesarean section. These scoring systems offer a rapid, low-cost, and non-invasive means of enhancing risk stratification in obstetric care. Incorporating such physiologic scoring systems into preoperative assessments may facilitate early intervention, improve maternal and neonatal outcomes, and support clinical decision-making.
Acknowledgements
The authors would like to thank Tony Karakas for his assistance with language editing and manuscript clarity.
Authors’ contributions
Study Conception and/or Design OB, PK. Data Processing, Collection, Perform Experiment PK, AB. Analysis and Interpretation of Results OB, MOO. Draft Manuscript Preparation, Visualization OB, BGC. Critical Revision or Editing of the Article OB, PK, AB. Final Approval of the Version to be Published OB,PK. Supervision, Funding Acquisition OB, AB, BGC. Other Contribution (if applicable please specify contribution) OB, PK, BGC. All authors reviewed the manuscript.
Funding
No specific funding was received for this study.
Data availability
Data is provided within the manuscript or supplementary information files.
Declarations
Ethics approval and consent to participate
This study was approved by the Süleyman Demirel University Clinical Research Ethics Committee (Decision No: 2022-04/61). Written informed consent was obtained from all participants before enrollment. The study was registered with ClinicalTrials.gov (NCT06488690).
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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Associated Data
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Data Availability Statement
Data is provided within the manuscript or supplementary information files.