Vertical transmission of SARS-CoV-2 infection in early pregnancy: what is the evidence?

It is today well-established that the early stages of pregnancy represent a particularly vulnerable period for the embryo and that viral infections during this period can potentially affect embryogenesis and fetal organ development. Viruses can gain access to the decidua and later to the placenta, by ascending from the lower reproductive tract, or via hematogenous transmission. Vertical transmission mechanisms are poorly understood. This reality calls for particular attention to women during early pregnancy in the present Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Unfortunately, except for scattered information [1], data regarding this crucial period are still lacking. Recent reports noted that pregnant women with novel Coronavirus Disease 2019 (COVID-19) had maternal vascular malperfusion and decidual arteriopathy in their placentas [2,3]. Moreover, Baud et al. [4] described a case of miscarriage during the second trimester in a CoVID-19 woman in whom the fetal surface of the placenta tested positive for SARS-CoV-2. Histopathology revealed mixed inflammatory infiltrates and funisitis, but it is unclear whether miscarriage occurred as a consequence of placental SARS-CoV-2 infection