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Changes in the treatment and outcomes of different severities of neonatal hypoxic ischemic encephalopathy in California: a retrospective cohort study

Journal of Perinatology volume 45, pages 1064–1072 (2025)Cite this article

Subjects

Abstract

Objective

Evaluate the changes in management and outcomes of Californian infants with hypoxic ischemic encephalopathy (HIE).

Study design

Infants with HIE were identified from a California administrative birth cohort using ICD codes and divided into two epochs, Epoch 1 (2010–2015) and Epoch 2 (2016–2019). Risk ratios (RR) for induced hypothermia (IH) in each epoch and their outcomes were calculated using log-linear regression.

Results

In this cohort, 4779 infants with HIE were identified. Incidence of HIE in California increased yearly from 0.5/1000 California births to a peak of 1.5/1000 births in 2018. The use of IH in infants with mild HIE increased in Epoch 2 compared to Epoch 1. There was no significant difference in outcomes between epochs for infants with mild HIE that received IH including no difference in neonatal seizures.

Conclusion

Significantly more infants with mild HIE received IH since 2015 in California, but no significant difference in outcomes.

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Fig. 1: Incidence of HIE in California.

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Data availability

All analyses were performed using Statistical Analysis Software version 9.4 (Cary, NC) with code available upon request.

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Acknowledgements

We would like to thank the Study of Mothers and Infants Research Group for their assistance. This study was supported by the San Diego Study of Mothers and Infants at the University of California San Diego and by the Rady Children’s Institute for Genomic Medicine. The data in this manuscript has been previously presented at: Western Society for Pediatric Research Conference, January 2023, Podium presentation. Cool Topics in Neonatology Conference, March 2023, Poster presentation. Pediatric Academic Societies Conference, May 2024, Poster presentation. The data in this manuscript has not been previously published or submitted for publication.

Funding

Gretchen Bandoli is funded by a NIH award (K01 AA027811) and the Rady Children’s Institute for Genomic Medicine.

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Authors and Affiliations

  1. University of Washington, Seattle Children’s Hospital, Seattle, WA, USA

    Carolyn Fall

  2. University of California San Diego, University of California San Francisco, San Francisco, CA, USA

    Rebecca J. Baer

  3. University of California, San Diego, Rady Children’s Hospital of San Diego, La Jolla, CA, USA

    Henry C. Lee, Gretchen Bandoli & Christina D. Chambers

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  1. Carolyn Fall
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  2. Rebecca J. Baer
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Contributions

Carolyn Fall formulated the research question, designed the study, and drafted the manuscript. Rebecca J. Baer performed the statistical analysis for this study. Gretchen Bandoli provided mentorship expertise on study design and manuscript editing. Henry C. Lee and Christina D. Chambers provided expertise in epidemiology, hypoxic ischemic encephalopathy, and manuscript editing.

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Correspondence to Carolyn Fall.

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Fall, C., Baer, R.J., Lee, H.C. et al. Changes in the treatment and outcomes of different severities of neonatal hypoxic ischemic encephalopathy in California: a retrospective cohort study. J Perinatol 45, 1064–1072 (2025). https://doi.org/10.1038/s41372-025-02212-5

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