Mechanisms and evidence of vertical transmission of infections in pregnancy including SARS-CoV-2s

Aniza P. Mahyuddin, Abhiram Kanneganti, Jeslyn J.L. Wong, Pooja S. Dimri, Lin L. Su, Arijit Biswas, Sebastian E. Illanes, Citra N.Z. Mattar, Ruby Y.J. Huang, Mahesh Choolani

Research output: Contribution to journalScientific reviewpeer-review

11 Scopus citations


There remain unanswered questions concerning mother-to-child-transmission of SARS-CoV-2. Despite reports of neonatal COVID-19, SARS-CoV-2 has not been consistently isolated in perinatal samples, thus definitive proof of transplacental infection is still lacking. To address these questions, we assessed investigative tools used to confirm maternal-fetal infection and known protective mechanisms of the placental barrier that prevent transplacental pathogen migration. Forty studies of COVID-19 pregnancies reviewed suggest a lack of consensus on diagnostic strategy for congenital infection. Although real-time polymerase chain reaction of neonatal swabs was universally performed, a wide range of clinical samples was screened including vaginal secretions (22.5%), amniotic fluid (35%), breast milk (22.5%) and umbilical cord blood. Neonatal COVID-19 was reported in eight studies, two of which were based on the detection of SARS-CoV-2 IgM in neonatal blood. Histological examination demonstrated sparse viral particles, vascular malperfusion and inflammation in the placenta from pregnant women with COVID-19. The paucity of placental co-expression of ACE-2 and TMPRSS2, two receptors involved in cytoplasmic entry of SARS-CoV-2, may explain its relative insensitivity to transplacental infection. Viral interactions may utilise membrane receptors other than ACE-2 thus, tissue susceptibility may be broader than currently known. Further spatial-temporal studies are needed to determine the true potential for transplacental migration.
Original languageAmerican English
JournalPrenatal Diagnosis
StatePublished - 1 Jan 2020

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