Vertical Transmission of COVID-19: A Systematic Review

Context: Evidence regarding the vertical transmission of COVID-19 from infected pregnant women to the fetus are not sufficient. Methods: The current study intended to systematically assess the possibility of vertical transmission of COVID-19 in published literature. We systematically searched international bibliographic databases, including PubMed, SCOPUS, and Google Scholar, to identify relevant studies from the time of inception of these databases until July 2020. The search strategy was finalized based on the results of the primary search in PubMed. All observational studies, including cross-sectional, cohort, case-control, case reports, and case series, published in peer-reviewed journals in any language. Editorials, commentaries, and letters to editors were excluded. Twenty articles (6 retrospective studies, 2 prospective, one cohort, 9 case reports, and 2 case series) with a total of 145 subjects were eligible for the review. Data were collected based on the preferred reporting items for systematic reviews and meta-analysis (PRISMA) checklist. Results: Methods of assessing COVID-19 included polymerase chain reaction (PCR) analysis of naso/oropharyngeal, vaginal, rectal, urine secretions and gastric and amniotic fluid samples, and serum immunoglobulin (Ig) assays. Vertical transmission was reported in 6 neonates (< 10%), based on PCR, and three were positive based on Ig assays. Conclusions: According to the evidence, the possibility for vertical transmission of COVID-19 is rare.