Combined Umbilical Artery -pH and Apgar Score Improve Neonatal Risk Assessment: JAMA
Researchers have found in a new study that integrating umbilical artery pH (UA-pH) with Apgar scores enhances estimation of risk for individual components of composite neonatal outcomes, supporting more accurate neonatal risk stratification. The study was published in JAMA Network Open by Harald E. and colleagues.
Very preterm (VPT) infants (born before 32 weeks’ gestation) have very high risks of mortality and severe neonatal morbidities. The 5-minute Apgar score is a standard tool for assessing the neonatal condition and guiding immediate care, but its prognostic utility in VPT infants has been questioned. Umbilical artery pH (UA-pH) reflects fetal acid–base status at birth and provides objective information about perinatal hypoxia and acidosis. Whether combining UA-pH with Apgar scores improves outcome prediction in VPT infants has remained uncertain and is addressed in this large, population-based investigation.
This cohort study obtained data from the Effective Perinatal Intensive Care in Europe (EPICE) project on infants born at less than 32 weeks of gestation from 11 European countries from April 2011 to September 2012. Of 7,900 liveborn VPT infants, 4,174 infants (52.8%) had complete data on both the 5-minute Apgar score and UA-pH and were included in this analysis. There were 2,249 males (53.9%) and 1,925 females (46.1%), with a median gestational age of 29.9 weeks and a median birth weight of 1,240 g. Analyses were performed between February and December 2025.
Key findings
The 5-minute Apgar score was categorized as lower than 7 or 7 and higher. UA-pH was categorized as low (<7.20) or normal (≥7.20).
Four combined exposure groups were defined based on these categories.
The main outcome was a mix of mortality and/or severe neonatal health issues.
This included intraventricular hemorrhage (IVH) greater than grade 2, cystic periventricular leukomalacia, moderate or severe bronchopulmonary dysplasia (BPD), retinopathy of prematurity stage 2 or higher, and necrotizing enterocolitis.
Secondary outcomes included mortality, IVH, and BPD analyzed separately.
Among the 4,174 infants studied, 367 infants (8.8%) had an Apgar score of 7 or higher with a low UA-pH. 558 infants (13.4%) had an Apgar score lower than 7 with a normal UA-pH, and 196 infants (4.7%) had both an Apgar score lower than 7 and a low UA-pH.
The remaining infants had an Apgar score of 7 or higher with a normal UA-pH and made up the reference group.
Infants with a 5-minute Apgar score lower than 7 had a much higher rate of the combined adverse outcome, regardless of UA-pH status.
Among infants with normal UA-pH, 48.4% of those with Apgar scores lower than 7 experienced the combined outcome, compared to 19.5% of those with Apgar scores of 7 or higher. Similar patterns occurred in infants with low UA-pH.
In this study of very preterm infants from a large European cohort, adding the pH of the umbilical artery and the 5-minute Apgar score to the risk prediction was found to enhance the accuracy of risks in relation to several early outcomes, especially mortality and intraventricular hemorrhage. This study endorses a more holistic approach to early neonatal assessment by stressing the necessity to assess early markers of risk in relation to neonatal outcome, rather than relying on a generalized early marker of risk.
Reference:
Ehrhardt H, Behboodi S, Maier RF, et al. Apgar Score Plus Umbilical Artery pH and Adverse Neonatal Outcomes in Very Preterm Infants. JAMA Netw Open. 2026;9(2):e2557913. doi:10.1001/jamanetworkopen.2025.57913
