Omicron SARS-CoV-2 maternal infection is associated with favorable fetomaternal outcomes and fewer placental vascular malperfusion lesions compared with previous variants
Abstract
BACKGROUND:The SARS-CoV-2 pandemic, declared in March 2020, has affected over 570 million people worldwide. The impact on pregnant women and fetuses remains unclear, particularly with the Omicron variant, which appears to increase the infection rates. OBJECTIVE: This retrospective study describes fetal-maternal complications and placental features in Omicron-variant SARS-CoV-2 infections during pregnancy and compares them with those associated with other variants and with noninfected controls from published studies examining the association between SARS-CoV-2 infection and placental pathology. STUDY DESIGN: We analyzed all consecutive placentas referred to our hospital from May 2021 to March 2023, associated with proven Omicron-variant SARS-CoV-2 maternal infection during pregnancy. RESULTS: Among the 315 placentas studied, fetal-maternal complication rates were comparable with those in the general population, including preeclampsia (0.6%), intrauterine growth restriction (5%), small for gestational age (9.1%), and preterm delivery (3.1%). We observed a significantly lower rate of hypotrophic placentas below the 10th percentile (4.1% vs 15.0% [P<0.001]), chronic deciduitis (3.8% vs 10.5% [P<0.01]), maternal vascular malperfusion (49.2% vs 58.8% [P<0.01]), and fetal vascular malperfusion lesions (7.6% vs 14.5% [P<0.001]) in the Omicron cohort vs published data from studies of individuals with non-Omicron variant SARS-CoV-2. We did not observe an increased incidence of chronic inflammation or the SARS-CoV-2 placentitis histologic triad in comparison to control cases from published data. A high rate of acute histological chorioamnionitis was observed, without an increased incidence in preterm deliveries. The interval between infection and delivery did not alter placental features. CONCLUSION: This large Omicron-variant placentas cohort highlighted clinically, an overall good outcome, and histologically significantly less vascular malperfusion and chronic deciduitis than in non-Omicron SARS-CoV-2 variants.
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BibTeX
@article{remoue2026omicron,
title = {{Omicron SARS-CoV-2 maternal infection is associated with favorable fetomaternal outcomes and fewer placental vascular malperfusion lesions compared with previous variants}},
author = {Annabelle Remoué and Yurina Suazo and Claire de Moreuil and Karine Morcel and Christophe Tremouilhac and Camille Sauvée and Arnaud Uguen and Pascale Marcorelles},
journal = {AJOG Global Reports},
year = {2026},
month = sep,
doi = {10.1016/j.xagr.2026.100690},
url = {https://univ-brest.hal.science/hal-05768476v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Omicron SARS-CoV-2 maternal infection is associated with favorable fetomaternal outcomes and fewer placental vascular malperfusion lesions compared with previous variants
AU - Annabelle Remoué
AU - Yurina Suazo
AU - Claire de Moreuil
AU - Karine Morcel
AU - Christophe Tremouilhac
AU - Camille Sauvée
AU - Arnaud Uguen
AU - Pascale Marcorelles
PY - 2026
DA - 2026/09/18
JO - AJOG Global Reports
DO - 10.1016/j.xagr.2026.100690
UR - https://univ-brest.hal.science/hal-05768476v1
AB - BACKGROUND:The SARS-CoV-2 pandemic, declared in March 2020, has affected over 570 million people worldwide. The impact on pregnant women and fetuses remains unclear, particularly with the Omicron variant, which appears to increase the infection rates. OBJECTIVE: This retrospective study describes fetal-maternal complications and placental features in Omicron-variant SARS-CoV-2 infections during pregnancy and compares them with those associated with other variants and with noninfected controls from published studies examining the association between SARS-CoV-2 infection and placental pathology. STUDY DESIGN: We analyzed all consecutive placentas referred to our hospital from May 2021 to March 2023, associated with proven Omicron-variant SARS-CoV-2 maternal infection during pregnancy. RESULTS: Among the 315 placentas studied, fetal-maternal complication rates were comparable with those in the general population, including preeclampsia (0.6%), intrauterine growth restriction (5%), small for gestational age (9.1%), and preterm delivery (3.1%). We observed a significantly lower rate of hypotrophic placentas below the 10th percentile (4.1% vs 15.0% [P<0.001]), chronic deciduitis (3.8% vs 10.5% [P<0.01]), maternal vascular malperfusion (49.2% vs 58.8% [P<0.01]), and fetal vascular malperfusion lesions (7.6% vs 14.5% [P<0.001]) in the Omicron cohort vs published data from studies of individuals with non-Omicron variant SARS-CoV-2. We did not observe an increased incidence of chronic inflammation or the SARS-CoV-2 placentitis histologic triad in comparison to control cases from published data. A high rate of acute histological chorioamnionitis was observed, without an increased incidence in preterm deliveries. The interval between infection and delivery did not alter placental features. CONCLUSION: This large Omicron-variant placentas cohort highlighted clinically, an overall good outcome, and histologically significantly less vascular malperfusion and chronic deciduitis than in non-Omicron SARS-CoV-2 variants.
SN - 2666-5778
SN - 2666-5778
ER -