Nearly a quarter of the 4 million neonatal deaths each year can be attributed to birth asphyxia. While a newborn’s metabolic stress during vaginal birth is important to prepare for life outside of the womb, persistent impairment of oxygen delivery can lead to metabolic acidosis and disruption to cellular metabolism. Birth asphyxia can also cause serious adverse events, including irreversible organ damage, hypoxic ischemic encephalopathy, intraventricular hemorrhage, cerebral palsy (CP), and impaired neuromotor development. Umbilical cord arterial pH (UApH) is a key measure for diagnosing neonatal acidemia. Conditions like CP have been associated with UApH <7.00; however, the evidence for this threshold is weak, and there is a lack of large-scale observational studies on the long-term adverse outcomes associated with neonatal acidemia. The aim of this study was to examine the association between UApH and long-term adverse outcomes. This was a retrospective cohort study, using data from singleton births at a single hospital in Malmö, Sweden, collected between January 1, 1997 and May 8, 2021. This data was cross-linked with data from the Swedish birth, patient, and death registries, with follow-up data obtained through 2017. Infants with UApH <7.05 were classified with neonatal acidemia, and those with UApH ≥7.05 were considered “non-acidemic.” A total of 35,931 infants were included in the analysis—with 912 (2.5%) classified with neonatal acidemia and 35,019 (97.5%) as non-acidemic. Overall, there was an increased risk of death in infants with UApH <7.05 at birth ( P = 0.043), but no significant differences were observed between the two groups for whole organ system diseases (ICD codes: 00 to 99). A subanalysis for mental and behavioral disorders found that the neonatal acidemia group had an increased risk of CP incidence 1.0% vs 0.2%; adjusted hazard ratio (HR), 4.35; 95% CI, 2.17- 8.73 and epilepsy (incidence, 1.6% vs 0.9%; adjusted HR, 1.71; 95% CI, 1.02-2.88). With a UApH <6.95, the HR for CP was 18.38 and 8.16 for epilepsy. No other significant differences were observed in the subanalysis. When the UApH was <7.10, the HR for CP increased progressively. However, at UApH <6.95, a significant difference was observed in the risk of CP, epilepsy, and intellectual disability. For those with UApH <6.95 at birth, the cumulative risk of being diagnosed with CP was 2.5% at 5 years of age and 5% at 20 years of age. Similarly, the cumulative risk of being diagnosed with epilepsy was 3% at 5 years of age and 12% at 20 years of age. In conclusion, neonatal acidemia was associated with an increased risk of death, but not for whole organ systems. However, a subanalysis of mental and behavioral disorders found an increased risk for CP and epilepsy in those with neonatal acidemia. (Summarized from Zaigham M, Källén K, Sundberg T-M, et al. Long-term outcomes after neonatal acidemia. Am J Obstet Gynecol. 2025;233(3):195.e1-11. doi: https://doi.org/10.1016/j.ajog.2025.02.028)
Aaron B. Caughey (Sun,) studied this question.