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Possibility of Vertical Transmission of COVID-19 During Pregnancy, Labor and After Delivery: A Systematic Review Study

Background: In general, although the placenta is a good barrier to prevent infections, several cases of coronavirus disease 19 (COVID-19) transmission have been reported during pregnancy. Moreover, considering the potential for vertical maternal-fetal transmission, there is a concern that the fetus is at risk for congenital COVID-19. The aim of the present review and systematic study was to investigate the possibility of the vertical transmission of COVID-19 during pregnancy, labor, and postpartum using available data. Methods: Studies conducted by February 12, 2021 were included in this systematic review study. Articles were searched in Medline, Magiran, SID, Civilica, Irandoc, ScienceDirect, PubMed, EMBASE, Web of Science, Scopus, and Google Scholar using English keywords such as "Coronavirus", "COVID-19, "SARS-CoV-2", "Vertical intrauterine transmission", "Vertical transmission", "Vertical fetal infection", "Maternal infection", and "Fetal infection". The inclusion criterion included all observational studies related to vertical maternal-fetal transmission. Overall, 31 articles were completely analyzed after reviewing and deleting non-eligible and duplicate articles. Results: The results of reviewing 24 studies showed that collected samples were all negative but positive blood samples, immunoglobulin M (IgM) and IgG antibodies, and expression of placental factors were reported in seven studies. Conclusion: Although contradictory results were found in this study, the results of the samples revealed the lowest probability of vertical transmission. There was also no evidence confirming the effectiveness of cesarean section in reducing the rate of transmission. In general, adherence to hygienic protocols can have a significant impact on reducing neonatal incidence.