INTRODUCTION Both intrauterine and intrapartum mother-to-child transmission of SARS-CoV-2 have been reported. However, there is still disagreement as to the likelihood and frequency of such vertical transmission.

OBJECTIVE Summarize and analyze the published evidence on forms of SARS-CoV-2 vertical transmission (either intrauterine or intrapartum).

EVIDENCE ACQUISITION We carried out a review of literature published in English and Spanish from January 1, 2020 through October 30, 2020. Search engines included PubMed/MEDLINE, SciELO, LILACS, Cochrane, Google Scholar, ResearchGate and medRxiv. There were no restrictions concerning type of study. The review included 48 original research articles, 11 review articles, a meta-analysis, 2 pre-published articles, 15 systematic reviews, and 10 editorials or comments.

DEVELOPMENT Medical thinking on congenital or intrapartum maternal–fetal/neonatal transmission of SARS-CoV-2 has evolved from preliminary evidence that was divided as to whether these forms of vertical transmission were even possible to current evidence support ing both forms of transmission and hypothesizing as to the mechanisms that guide them. The presence of the SARS-CoV-2 virus in maternal, placental, fetal or neonatal tissues has been demonstrated by RT-PCR, specific immunoglobulin detection tests, immunostaining and in-situ hybridization. It is estimated that infections acquired either congenitally or intrapartum occur in 1.8%–8.0% of newborns born to women who test positive for COVID-19 at the end of their pregnancies. This review found 53 neonates who were diagnosed with COVID-19 in the first 48 hours of life by either RT-PCR or specific IgM tests. According to criteria outlined in this review, the timing of infection corresponded to congenital or intrapartum transmission in 39.6% (21/53) of COVID-19–positive newborns, to postpartum transmission in 15.1% (8/53) and remains unspecified in 45.3% (24/53).

CONCLUSIONS Congenital and intrapartum SARS-CoV-2 infection in the fetus/newborn is possible, but rare. International collaborative studies using common epidemiological surveillance instruments would allow for a more precise specification of the frequency of congenital and intrapartum SARS-CoV-2 infection at the population level.

KEYWORDS COVID-19; SARS-CoV-2; vertical transmission of infectious disease; infant, newborn