Genes which allow COVID-19 infection to take hold are present in the first trimester of pregnancy, researchers report today.
The consequences of COVID-19 infection for the embryo are largely unaddressed, say Professor Magdalena Zernicka-Goetz of the University of Cambridge, UK, and colleagues.
They explain in Open Biology today (5 August) that conflicting clinical reports have emerged regarding infection in neonates whose mothers were infected. Some studies found no evidence for vertical transmission from mother to embryo, but others found none. In addition, little is known about the risks of vertical transmission in early pregnancy.
The team looked for the earliest stage at which the SARS-CoV-2 receptor, angiotensin-converting enzyme 2, is first expressed and the human embryo could possibly become infected.
They found expression of the relevant genes at the stage of implantation, which they write: “Raise the possibility of vertical transmission and indicates that further work is required to understand potential risks to implantation, placental health and foetal health that require further study”.
Professor Zernicka-Goetz said: “Our work suggests that the human embryo could be susceptible to COVID-19 as early as the second week of pregnancy if the mother gets sick. “
Co-author Professor David Glover commented: “Genes encoding proteins that make cells susceptible to infection by this novel coronavirus become expressed very early on in the embryo’s development.
“This is an important stage when the embryo attaches to the mother’s womb and undertakes a major remodelling of all of its tissues and for the first time starts to grow. COVID-19 could affect the ability of the embryo to properly implant into the womb or could have implications for future foetal health.”
Weatherbee, B. A. T. et al. Expression of SARS-CoV-2 receptor ACE2 and the protease TMPRSS2 suggests susceptibility of the human embryo in the first trimester. Open Biology 5 August 2020 doi: 10.1098/rsob.200162
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