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. 2026 Feb 2;9(2):e2557913.
doi: 10.1001/jamanetworkopen.2025.57913.

Apgar Score Plus Umbilical Artery pH and Adverse Neonatal Outcomes in Very Preterm Infants

Harald Ehrhardt  1   2 , Soodabeh Behboodi  3 , Rolf F Maier  4 , Adrien M Aubert  3 , Ulrika Ådén  5   6 , Birte Staude  1   3 , Elizabeth S Draper  7 , Anna Gudmundsdottir  5 , Veronica Siljehav  5 , Heili Varendi  8 , Tom Weber  9 , Michael Zemlin  10 , Jennifer Zeitlin  3 ; EPICE/SHIPS Research Group
Collaborators, Affiliations

Apgar Score Plus Umbilical Artery pH and Adverse Neonatal Outcomes in Very Preterm Infants

Harald Ehrhardt et al. JAMA Netw Open. .

Abstract

Importance: The Apgar score, the first clinical assessment to direct measures to stabilize newborn infants, is also used for risk assessment. Its accuracy in estimating outcomes remains poor among very preterm (VPT) infants.

Objective: To assess the utility of the combined 5-minute Apgar score and umbilical artery pH (UA-pH) for estimating risks of mortality and severe neonatal morbidity among VPT infants.

Design, setting, and participants: This cohort study (Effective Perinatal Intensive Care in Europe [EPICE]) analyzed infants born at less than 32 weeks' gestation between April 2011 and September 2012 across 11 European countries. All liveborn VPT infants with Apgar scores and UA-pH data were included. Data were analyzed between February and December 2025.

Exposures: Apgar score at 5 minutes and UA-pH. The Apgar score was classified as lower than 7 and 7 or higher, and the UA-pH values were categorized as low (<7.20) and normal (≥7.20). Four groups that combined these 2 measures were defined: Apgar score lower than 7 and low UA-pH; Apgar score lower than 7 and normal UA-pH; Apgar score 7 or higher and low UA-pH; and Apgar score 7 or higher and normal UA-pH.

Main outcomes and measures: Combined outcome of mortality and/or any adverse morbidity (intraventricular hemorrhage [IVH] >grade 2, cystic periventricular leukomalacia, moderate or severe bronchopulmonary dysplasia [BPD], retinopathy of prematurity ≥stage 2, and necrotizing enterocolitis). Modified Poisson regression was used to estimate relative risks (RRs) between the exposure and the combined mortality and morbidity outcome and 3 individual components: mortality, IVH, and BPD. Models were adjusted for perinatal variables associated with Apgar score and UA-pH and adverse neonatal outcomes.

Results: Of 7900 liveborn infants in the EPICE cohort, 4174 (52.8%) had information on Apgar score and UA-pH. These infants included 2249 males (53.9%) and had a median [IQR] gestational age of 29.9 [27.9-31.0] weeks and median [IQR] birth weight of 1240 [960-1520] g. A total of 367 infants (8.8%) had an Apgar score 7 or higher but a low UA-pH, 558 (13.4%) had an Apgar score lower than 7 but a normal UA-pH, and 196 (4.7%) had an Apgar score lower than 7 and a low UA-pH. Infants with an Apgar score lower than 7 had a higher frequency of the combined outcome among those with a normal UA-pH (270 [48.4%] vs 596 [19.5%]) and a low UA-pH (108 [55.1%] vs 596 [19.5%]), with similar adjusted RRs (ARRs; low: 1.4 [95% CI, 1.2-1.7]; normal: 1.4 [95% CI, 1.3-1.6]). For mortality risk, associations were robust for an Apgar score lower than 7 and a low UA-pH (ARR, 2.4; 95% CI, 1.7-3.3) and absent with an Apgar score of 7 or higher and a low UA-pH (ARR, 1.2; 95% CI, 0.8-1.8). IVH risk was increased in all 3 subcategories, including an Apgar score of 7 or higher with a low UA-pH (ARR, 2.0; 95% CI, 1.3-3.0). BPD risk was associated only with an Apgar score lower than 7 and a normal UA-pH (ARR, 1.4; 95% CI, 1.2-1.7).

Conclusions and relevance: In this cohort study of VPT infants, combining information on UA-pH with the 5-minute Apgar score was associated with improved accuracy in estimating the risk of some adverse outcomes-notably mortality and IVH, which occurred soon after birth. These results highlight the importance of exploring the associations of early markers of risk with neonatal mortality and key neonatal morbidities separately.

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Conflict of interest statement

Conflict of Interest Disclosures: Dr Ehrhardt reported being a member of the special interest group Preterm Birth of the European Association of Perinatal Medicine, Pulmonology section, and the special interest group Sub 25/40 Preterm Infants and the Pulmonary Research Consortium of the European Society of Pediatric Research outside the submitted manuscript. Dr Maier reported receiving grants from the European Union Seventh Framework Programme during the conduct of the study. Dr Siljehav reported receiving grants from the Swedish Research Counsil during the conduct of the study. Dr Varendi reported receiving grants from the University of Tartu during the conduct of the study. Prof Zeitlin reported receiving grants from the European Commission during the conduct of the study. No other disclosures were reported.

Figures

Figure 1.
Figure 1.. Flowchart of Patient Allocation to the Apgar Score and Umbilical Artery pH (UA-pH) Categories
EPICE indicates Effective Perinatal Intensive Care in Europe; VPT, very preterm.
Figure 2.
Figure 2.. Dot Graph of Severe Acute Outcomes in Infants With Less Than 32 Weeks’ Gestation by Apgar Score and Umbilical Artery pH (UA-pH)
Data were analyzed using modified Poisson regression without adjustments except for country (blue squares) and after adjustment in full model (orange squares) for maternal age, perinatal variables (gestational age, small for gestational age, sex, multiple birth, congenital anomaly), pregnancy complications (preterm rupture of membranes, hypertensive disorders of pregnancy), parity, mode of delivery, antenatal steroid administration, and inborn status. Infants with Apgar score of 7 or higher and UA-pH of 7.20 or higher served as the reference group in the modified Poisson regression models. ARR indicates adjusted relative risk; IVH, intraventricular hemorrhage; BPD, bronchopulmonary dysplasia.
See this image and copyright information in PMC

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