Buy Article Permissions and Reprints Abstract

Objective Pregnant women are at increased risk of coronavirus disease 2019 (COVID-19). This could be explained through the prism of physiologic and immunologic changes in pregnancy. In addition, certain immunological reactions originate in the placenta in response to viral infections.

This study aimed to investigate whether severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) can infect the human placenta and discuss its implications in the pathogenesis of adverse pregnancy outcomes.

Study Design We conducted a retrospective cohort study in which we collected placental specimens from pregnant women who had a laboratory-confirmed SARS-CoV-2 infection. We performed RNA in situ hybridization assay on formalin-fixed paraffin-embedded tissues to establish the in vivo evidence for placental infectivity by this corona virus. In addition, we infected trophoblast isolated from uninfected term human placenta with SARS-CoV-2 variants to further provide in vitro evidence for such an infectivity.

Results There was a total of 21 cases enrolled, which included 5 cases of spontaneous preterm birth (SPTB) and 2 intrauterine fetal demises (IUFDs). Positive staining of positive-sense strand of SARS-CoV-2 virions was detected in 15 placentas including 4 SPTB and both IUFDs. In vitro infection assay demonstrated that SARS-CoV-2 virions were highly capable of infecting both cytotrophoblast and syncytiotrophoblast.

Conclusion This study implies that placental SARS-CoV-2 infection may be associated with an increased risk of adverse obstetrical outcomes.

Key Points

SARS-CoV-2 can effectively infect human placenta.

Such infectivity is confirmed by in vitro experiments.

Placental SARS-CoV-2 corelates with adverse obstetrical outcomes.

Keywords placenta - SARS-CoV-2 - adverse pregnancy outcomes - intrauterine fetal demise - preterm birth Authors' Contributions

B.W. and P.Y. conceived the study. B.W., W-B.S., L.B., and J.L. performed the experiments. B.W., C.T., E.A.R., M.B.F., and P.Y. analyzed and interpreted the data. B.W., C.T., E.A.R., M.B.F., and P.Y. cowrote the paper.

Publication History

Received: 05 April 2024

Accepted: 07 May 2024

Accepted Manuscript online:
10 May 2024

Article published online:
10 June 2024

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