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Cerebral Palsy Risk by Combined Apgar Score and Umbilical Cord Blood pH Levels
Mette Vestergård Pedersen1,2, Morten Søndergaard Lindhard2,3, Dag Moster4,5
1Department of Pediatrics and Adolescent Medicine, Aarhus University Hospital, Aarhus, Denmark.
JAMA Network Open
|February 18, 2026
Summary
Perinatal hypoxia, indicated by low Apgar scores and umbilical cord pH, significantly increases cerebral palsy (CP) risk. Combined abnormalities yield the highest CP risk, informing targeted follow-up for newborns.
Area of Science:
- Neonatal care
- Neurology
- Public health
Background:
- Perinatal hypoxia is a major cause of cerebral palsy (CP).
- Current criteria for relevant perinatal hypoxia require both clinical (Apgar score) and biochemical (umbilical cord blood pH) abnormalities.
- Most studies have examined only one measure of perinatal hypoxia, limiting understanding of combined effects.
Purpose of the Study:
- To investigate the association between perinatal hypoxia, assessed by combined Apgar score and umbilical cord blood pH, and the risk of cerebral palsy.
- To evaluate the impact of combined clinical and biochemical markers of perinatal hypoxia on CP development.
Main Methods:
- A nationwide registry-based cohort study in Denmark included singleton newborns (gestational age ≥35 weeks) from 2004-2018.
- Perinatal hypoxia was assessed using combinations of 5-minute Apgar scores (0-3, 4-6, 7-10) and umbilical cord blood pH categories (<7.00, 7.00-7.09, 7.10-7.19, ≥7.20).
- Associations with CP were analyzed using multivariable log-binomial regression, with severe CP defined by Gross Motor Function Classification System levels IV-V.
Main Results:
- The cohort comprised 825,159 newborns.
- Infants with the lowest Apgar score (0-3) and lowest pH (<7.00) had a 15.2% CP diagnosis rate (aRR 159.0).
- Even with a normal Apgar score, the lowest pH (<7.00) increased CP risk (aRR 6.1), and the lowest Apgar score with normal pH (≥7.20) also elevated risk (aRR 22.0).
- Severe CP was significantly more common when both Apgar score and pH were abnormal (49.2%) compared to normal (10.1%).
Conclusions:
- Perinatal hypoxia, assessed by both clinical (Apgar) and biochemical (pH) measures, is strongly associated with CP risk.
- The risk of CP is substantially higher when both Apgar score and umbilical cord blood pH are abnormal.
- These findings highlight the importance of using combined measures for identifying infants at risk for CP and guiding follow-up care.
