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Infectious Diseases

Poster Session 2

(591) Association of SARS-CoV-2 variant type and placental pathology changes

Tuesday, February 13, 2024
3:30 PM – 5:00 PM  
Location: Prince George's Exhibit Hall CDE, Lower Atrium Level
Objective: Pregnant people infected with SARS CoV-2 are at risk for increased disease severity and complications with level of risk varying across genotypic viral variants (pre-delta, delta, omicron). We sought to investigate the association between viral variant and placental pathology changes in pregnant patients with SARS CoV-2.

Study Design: This was a retrospective cohort study of pregnant patients diagnosed with PCR-confirmed SARS CoV-2 (3/2020-4/2022) who delivered at a single institution. Variant type was based on genotypic sequencing data at our institution: pre-delta 3/2020-6/2021, delta 7/2021-12/15/2021, and omicron 12/16/21-4/2022. Primary outcomes were placental pathology findings characteristic of SARS CoV-2 placentitis: chronic histiocytic intervillositis, massive perivillous fibrinoid deposition, and trophoblast necrosis. Secondary outcomes included additional descriptors of placental pathology and infant variables.

Results: A total of 530 women were included in the study and 406 (76%) had placental pathology available. Among these 406, 37% were admitted with a PCR-confirmed SARS CoV-2 test during the pre-delta period, 26% during delta, and 37% during omicron variant waves. Pregnant women admitted during the omicron wave were more likely to be vaccinated, and had milder disease severity (all p< 0.01). We found no difference in placental pathology by variant wave. Chorionic villous ischemic changes were the only findings that were significantly different across variant waves, with higher rates seen in pre-delta and delta compared to omicron (p< 0.01). Infant birthweight < 10th percentile (p=0.04) and infant head circumferences < 10th percentile (p=0.01) were also significantly different with the highest rates seen in the pre-delta wave.

Conclusion: The majority of placental pathology features were similar across SARS CoV-2 variant types. SARS CoV-2 placentitis overall is a rare occurrence, and in our cohort appeared confined to the pre-delta and delta waves.