Umbilical Cord Blood pH Level, Apgar Score, and Attention-Deficit/Hyperactivity Disorder.

Area of Science:

• Neuroscience
• Pediatrics
• Public Health

Background:

• Perinatal hypoxia is a known risk factor for neurodevelopmental impairments, including attention-deficit/hyperactivity disorder (ADHD).
• Accurate assessment of perinatal hypoxia requires evaluating both clinical (Apgar score) and biochemical (umbilical cord blood pH) markers.
• Previous studies often relied solely on Apgar scores, potentially underestimating hypoxia-related risks.

Purpose of the Study:

• To identify newborns exposed to perinatal hypoxia using combined Apgar score and umbilical cord blood pH criteria.
• To investigate the association between this combined hypoxia assessment and the subsequent development of ADHD.

Main Methods:

• A nationwide Danish cohort study included singleton newborns (gestational age ≥35 weeks) from 2004-2018.
• Hypoxia was categorized by combinations of 5-minute Apgar scores (0-3, 4-6, 7-10) and umbilical cord blood pH (<7.10, 7.10-7.19, ≥7.20).
• ADHD outcomes were determined by hospital diagnoses and medication prescriptions, with data analyzed using adjusted odds ratios and multiple imputation.

Main Results:

• The study analyzed 819,658 newborns; 0.3% had both a low Apgar score (0-3) and low pH (<7.10).
• Increased ADHD odds were observed for combinations with pH <7.20 and Apgar <7, most significantly with Apgar 0-3 and pH <7.10 (aOR=1.86).
• No association between Apgar score and ADHD was found if pH was ≥7.20, nor between pH and ADHD if Apgar score was ≥7.

Conclusions:

• Combined clinical and biochemical indicators of perinatal hypoxia (low Apgar score and low umbilical cord pH) are associated with increased odds of ADHD.
• The absence of increased ADHD risk when either Apgar score or pH is normal suggests these combined measures are critical for identifying at-risk neonates.
• This finding underscores the importance of comprehensive perinatal assessment for predicting neurodevelopmental outcomes like ADHD.