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Impact of COVID-19 respiratory conditions on pregnancy outcomes in California

Journal of Perinatology (2026)Cite this article

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Abstract

Objectives

The objective of this study is to identify the populations at greatest risk for COVID-19 complications during pregnancy and determine their adverse maternal and neonatal outcomes in a time period prior to vaccine availability.

Study design

Cohort study using delivery hospitalization discharge data linked to vital records for all births in California during the baseline pre-COVID-19 period and for all births during the COVID-19 Study period.

Results

Among 344,894 deliveries, a total of 7181 (2.08%) hospitalized patients tested positive for COVID-19 during pregnancy. Of these, 571 (0.17%) patients were hospitalized with severe respiratory illness. Rate of severe maternal morbidity (242/571, 42%) and maternal death (10/571, 1.8%) were markedly elevated in those hospitalized patients with COVID-19 related respiratory disease compared to both uninfected parturients and infected parturients with less severe disease. Higher rates of COVID-19 related respiratory conditions were associated with Hispanic ethnicity, Native American race, state-funded insurance, and lower education levels.

Conclusion

In pregnancies complicated by COVID-19, the excess risks of maternal mortality, SMM, and adverse neonatal outcomes were restricted to the patients with COVID-19 related respiratory conditions. Significant disparities were noted for respiratory conditions, mortality and SMM related to race-ethnicity and socioeconomic status.

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Fig. 1: Forest plots of adjusted relative risk (aRR) and 95% confidence interval (CI) for the association between maternal characteristics and COVID-19 infection during pregnancy.

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Author information

Authors and Affiliations

  1. Obstetrics and Gynecology, Hoag Specialty Clinic, Newport Beach, CA, USA

    Courtney B. Martin

  2. California Maternal Quality Care Collaborative, Stanford University, Stanford, CA, USA

    Shen-Chih Chang, Christa Sakowski, Jeffrey B. Gould & Elliott K. Main

  3. Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA

    Shen-Chih Chang, Jeffrey B. Gould & David K. Stevenson

  4. Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, CA, USA

    Natali Aziz & Elliott K. Main

Authors
  1. Courtney B. Martin
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  2. Shen-Chih Chang
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  4. Natali Aziz
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  5. Jeffrey B. Gould
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  6. David K. Stevenson
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  7. Elliott K. Main
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Contributions

CM conceptualized and led the study, contributed to study design, interpreted results, and drafted the manuscript. S-CC contributed to study design, performed statistical analyses, and critically revised the manuscript. CS assisted with data acquisition and manuscript drafting. NA contributed to interpretation of findings and manuscript review. JG provided methodological guidance and editorial input. DS contributed to study conceptualization and critical manuscript review. EM oversaw the project, advised on study design and data interpretation, and reviewed the manuscript for final approval. All authors reviewed and approved the final version of the manuscript.

Corresponding author

Correspondence to Elliott K. Main.

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Competing interests

The authors declare no competing interests.

Ethics approval and consent to participate

All methods were performed in accordance with relevant guidelines and regulations. Ethics approval was obtained from Stanford University Institutional Review Board and the California Committee for the Protection of Human Subjects (CPHS) for the use of linked administrative and vital records data. This study used de-identified data. Informed consent from individual participants was not required or applicable. No identifiable images or personal identifiers are included in this publication.

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Martin, C.B., Chang, SC., Sakowski, C. et al. Impact of COVID-19 respiratory conditions on pregnancy outcomes in California. J Perinatol (2026). https://doi.org/10.1038/s41372-025-02550-4

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