key: cord-0771038-vhzdbc8l
authors: Valk, Jacob E.; Chong, Alexander M.; Uhlemann, Anne-Catrin; Debelenko, Larisa
title: Detection of SARS-CoV-2 in placental but not fetal tissues in the second trimester
date: 2020-11-30
journal: J Perinatol
DOI: 10.1038/s41372-020-00877-8
sha: 8759e4c5d0947b93266d939cbe00bfbfb620a7ef
doc_id: 771038
cord_uid: vhzdbc8l

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premature rupture of membranes at 18+ weeks and delivered a non-viable female fetus. A 29 year-old gravida 1 para 0 presented in labor at 23+ weeks and delivered a male neonate with Apgar scores 2, 2, and 2. A cardiac arrest was registered on 8 min of life and resuscitation was unsuccessful. The neonatal nasal swab test for SARS-CoV-2 was negative.

Placental and fetal pathologies as well as results of the tissue viral studies are presented in Table 1 . SARS-CoV-2 qRT-PCR was positive in placentas and negative in fetal organs in both cases. Neither placentas, nor fetal organs stained for the virus by IHC and ISH. This discrepancy can be explained by a much lower sensitivity of IHC and ISH, comparing to RT-PCR. To date, we found at least ten reported cases of SARS-CoV-2 detected in the placental tissue by RT-PCR [1] [2] [3] [4] [5] and only in five cases was the virus demonstrated by IHC and/or ISH [2, 3] .

Lack of viral sequences in umbilical cords and fetal organs argues against a vertical transmission of SARS-CoV-2, while the presence of placental and fetal pathologies previously established to be associated with fetal demise can explain the abortion and the preterm labor. In the 1st case, the placenta showed chronic deciduitis (Supplementary Fig. 1 ), which is known to be associated with an abnormal immune response to pregnancy and spontaneous abortions with normal karyotype. In the 2nd case, placental and neonatal pulmonary pathologies provided a convincing evidence of involvement by Group B Streptococcus agalactiae (Supplementaty Fig. 2) , a known cause of premature labor and neonatal death.

We demonstrated SARS-CoV-2 involvement of placentas detectable by qRT-PCR in asymptomatic COVID-19-infected pregnant women in the second trimester. Our data are in accord with published reports on the low incidence of vertical transmission of the virus. However, more data are needed to determine the overall feto-maternal risks of SARS-CoV-2 infection at different terms of gestation. 

Probable congenital SARS-CoV-2 infection in a neonate born to a woman with active SARS-CoV-2 infection

Transplacental transmission of SARS-CoV-2 infection

SARS-CoV-2 infection of the placenta

Second-trimester miscarriage in a pregnant woman with SARS-CoV-2 infection

Detection of SARS-COV-2 in Placental and Fetal Membrane Samples

Detection of SARS-CoV-2 in placental but not fetal tissues in the second trimester

Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.Author contributions JEV acquired data and wrote the manuscript, AMC conducted experiments and edited the manuscript, ACU designed experiments and edited the manuscript, LD collected material, supervised the study and edited the manuscript.

Conflict of interest The authors declare that they have no conflict of interest.Publisher's note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.