Performance of a Maternal Risk Stratification System for Predicting Low Apgar Scores

Abstract

Objective Maternal risk stratification systems are increasingly employed in predicting and preventing obstetric complications. These systems focus primarily on maternal morbidity, and few tools exist to stratify neonatal risk. We sought to determine if a maternal risk stratification score was associated with neonatal morbidity.

Study Design Retrospective cohort study of patients with liveborn infants born at ≥24 weeks at four hospitals in one health system between January 1, 2020, and December 31, 2020. The Expanded Obstetric Comorbidity Score (EOCS) is used as the maternal risk score. The primary neonatal outcome was 5-minute Apgar <7. Logistic regression models determined associations between EOCS and neonatal morbidity. Secondary analyses were performed, including stratifying outcomes by gestational age and limiting analysis to “low-risk” term singletons. Model discrimination assessed using the area under the receiver operating characteristic curves (AUC) and calibration via calibration plots.

Results A total of 14,497 maternal–neonatal pairs were included; 236 (1.6%) had 5-minute Apgar <7; EOCS was higher in 5-minute Apgar <7 group (median 41 vs. 11, p < 0.001). AUC for EOCS in predicting Apgar <7 was 0.72 (95% Confidence Interval (CI) 0.68, 0.75), demonstrating relatively good discrimination. Calibration plot revealed that those in the highest EOCS decile had higher risk of neonatal morbidity (7.6 vs. 1.7%, p < 0.001). When stratified by gestational age, discrimination weakened with advancing gestational age: AUC 0.70 for <28 weeks, 0.63 for 28 to 31 weeks, 0.64 for 32 to 36 weeks, and 0.61 for ≥37 weeks. When limited to term low-risk singletons, EOCS had lower discrimination for predicting neonatal morbidity and was not well calibrated.

Conclusion A maternal morbidity risk stratification system does not perform well in most patients giving birth, at low risk for neonatal complications. The findings suggest that the association between EOCS and 5-minute Apgar <7 likely reflects a relationship with prematurity. This study cautions against intentional or unintentional extrapolation of maternal morbidity risk for neonatal risk, especially for term deliveries.

Key Points

• EOCS had moderate discrimination for Apgar <7.

• Predictive performance declined when limited to low-risk term singletons.

• Relationship between EOCS and Apgar <7 was likely driven by prematurity.

Keywords

risk prediction - neonatal morbidity - maternal morbidity - adverse neonatal outcomes - pregnancy complications - risk score - risk stratification

Note

The abstract was presented as a Poster Presentation at the 42nd Annual Meeting for the Society of Fetal Medicine (SMFM Abstract #744), which was held virtually from January 31 to February 5, 2022.

Publication History

Received: 29 September 2023

Accepted: 30 January 2024

Accepted Manuscript online:
01 February 2024

Article published online:
01 March 2024

• References

• 1 Bateman BT, Mhyre JM, Hernandez-Diaz S. et al. Development of a comorbidity index for use in obstetric patients. Obstet Gynecol 2013; 122 (05) 957-965
• 2 Easter SR, Bateman BT, Sweeney VH. et al. A comorbidity-based screening tool to predict severe maternal morbidity at the time of delivery. Am J Obstet Gynecol 2019; 221 (03) 271.e1-271.e10
• 3 Arnolds DE, Smith A, Banayan JM, Holt R, Scavone BM. National partnership for maternal safety recommended maternal early warning criteria are associated with maternal morbidity. Anesth Analg 2019; 129 (06) 1621-1626
• 4 Leonard SA, Kennedy CJ, Carmichael SL, Lyell DJ, Main EK. An expanded obstetric comorbidity scoring system for predicting severe maternal morbidity. Obstet Gynecol 2020; 136 (03) 440-449
• 5 Alfirevic Z, Devane D, Gyte GM, Cuthbert A. Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour. Cochrane Database Syst Rev 2017; 2 (02) CD006066
• 6 Grimes DA, Peipert JF. Electronic fetal monitoring as a public health screening program: the arithmetic of failure. Obstet Gynecol 2010; 116 (06) 1397-140
• 7 Casey BM, McIntire DD, Leveno KJ. The continuing value of the Apgar score for the assessment of newborn infants. N Engl J Med 2001; 344 (07) 467-471
• 8 Razaz N, Cnattingius S, Joseph KS. Association between Apgar scores of 7 to 9 and neonatal mortality and morbidity: population based cohort study of term infants in Sweden. BMJ 2019; 365: l1656
• 9 Thorngren-Jerneck K, Herbst A. Low 5-minute Apgar score: a population-based register study of 1 million term births. Obstet Gynecol 2001; 98 (01) 65-70
• 10 Duncan JR, Sawangkum P, Hoover EA, Aziz MM, Vilchez G. Birthweight and Apgar at 5 minutes of life for the prediction of severe neonatal outcomes in preterm prelabor rupture of membranes. J Matern Fetal Neonatal Med 2022; 35 (23) 4521-4525
• 11 Centers for Disease Control and Prevention. How Does CDC Identify Severe Maternal Morbidity? Published on April 10, 2023. Accessed June 25, 2023 at: https://www.cdc.gov/reproductivehealth/maternalinfanthealth/smm/severe-morbidity-ICD.htm
• 12 The Joint Commission. Specifications Manual for the Joint Commission: PC-06 (2019). Accessed January 1, 2021 at: https://manual.jointcommission.org/releases/TJC2019A/MIF0393.html
• 13 Clapp MA, James KE, Bates SV, Kaimal AJ. Patient and hospital factors associated with unexpected newborn complications among term neonates in US hospitals. JAMA Netw Open 2020; 3 (02) e1919498
• 14 Ratnasiri AWG, Lakshminrusimha S, Dieckmann RA. et al. Maternal and infant predictors of infant mortality in California, 2007–2015. PLoS ONE 2020; 15 (08) e0236877
• 15 Shukla VV, Eggleston B, Ambalavanan N. et al. Predictive modeling for perinatal mortality in resource-limited settings. JAMA Netw Open 2020; 3 (11) e2026750
• 16 Raineau M, Deneux-Tharaux C, Seco A, Bonnet MP. EPIMOMS Study Group. Antepartum severe maternal morbidity: a population-based study of risk factors and delivery outcomes. Paediatr Perinat Epidemiol 2022; 36 (02) 171-180
• 17 Mengistu TS, Schreiber V, Flatley C, Fox J, Kumar S. Factors associated with increased risk of early severe neonatal morbidity in late preterm and early term infants. J Clin Med 2021; 10 (06) 1319
• 18 The Joint Commission. R3 Report Issue 24: PC Standards for Maternal Safety. (2020) Accessed June 25, 2023 at: https://www.jointcommission.org/standards/r3-report/r3-report-issue-24-pc-standards-for-maternal-safety/