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Review
. 2021 Jan 8;11(1):94.
doi: 10.3390/diagnostics11010094.

The Effects of COVID-19 on Placenta and Pregnancy: What Do We Know So Far?

Yin Ping Wong  1 , Teck Yee Khong  2 , Geok Chin Tan  1
Affiliations
Review

The Effects of COVID-19 on Placenta and Pregnancy: What Do We Know So Far?

Yin Ping Wong et al. Diagnostics (Basel). .

Abstract

The current coronavirus disease 2019 (COVID-19) pandemic, caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has inflicted a serious health crisis globally. This virus is associated with a spectrum of respiratory illness ranging from asymptomatic, mild to severe pneumonia, and acute respiratory distress syndrome. Accumulating evidence supports that COVID-19 is not merely a respiratory illness per se, but potentially affects other organ systems including the placenta. SARS-CoV-2 gains access to human cells via angiotensin-converting enzyme 2 (ACE-2). The abundance of ACE-2 on the placental cell surface, especially the syncytiotrophoblasts, could potentially contribute to vertical transplacental transmission to the fetus following maternal COVID-19 infection. Intriguingly, despite the placentas being tested positive for SARS-CoV-2, there are very few newborns that manifest virus-induced diseases. The protective effects of the placental barrier to viral infection, limiting the spread of the virus to newborn infants, remain a mystery. The detrimental role of COVID-19 in pregnancies is largely debatable, although COVID-19 maternal infection has been implicated in unfavorable pregnancy outcomes. In this review, we summarize the pathological features manifested in placenta due to COVID-19 maternal infection that have been previously reported, and relate them to the possible disease manifestation. The potential mechanistic pathways associated with transplacental viral transmission and adverse pregnancy outcomes are also discussed.

Keywords: COVID-19; SARS-CoV-2; pathology; placenta; pregnancy.

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Conflict of interest statement

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Figures

Figure 1
Figure 1
Frequency of reported histopathological features of. SARS-CoV-2-infected second and third trimester placentas (n = 36).
Figure 2
Figure 2
Maternal–fetal interplay following SARS-CoV-2 infection, reported histomorphological alterations in infected placenta, and adverse pregnancy outcomes. Abbreviations: ACE2: Angiotensin converting enzyme 2; FIRS: Fetal inflammatory response syndrome; IL-6: Interleukin-6; TNF-α: Tumor necrosis factor-α; TMPRSS2: Transmembrane serine protease 2.
See this image and copyright information in PMC

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