Expecting moms can pass on COVID-19 to babies, but the risk is relatively low: research

On Tuesday, 14 July 2020, two research papers came out on the topic of vertical transmission (from expecting mom to the foetus) of COVID-19.

The first, published in Nature Communication, reported on the life journey of this Parisian baby so far: the doctors found evidence of the SARS-CoV-2 virus in the amniotic fluid that was collected from the mom before they ruptured her amniotic sac to deliver the baby. They also found the virus in the placenta, in the baby’s blood and the fluid from his lungs. They also found inflammation in the placenta. All of which, the medical researchers said, point to COVID-19 infection in the womb.

This may be the first case anywhere in the world, in which doctors were able to collect samples and monitor the mom and baby closely to confirm vertical transmission.

As they wrote in their article: “We report a proven case of transplacental transmission of SARS-CoV-2 from a pregnant woman affected by COVID-19 during late pregnancy to her offspring. Other cases of potential perinatal transmission have recently been described, but presented several unaddressed issues. For instance, some failed to detect SARS-CoV-2 in neonates or only reported the presence of specific antibodies; others found the virus in the newborn samples but the transmission route was not clear as placenta, amniotic fluid and maternal or newborn blood were not systematically tested in every mother-infant pair.”

In other words, these researchers didn’t just find COVID-19 antibodies in the baby’s blood, but they were able to test the viral load in the mom and baby over several days after birth and they were able to say with reasonable confidence that the virus spread from mom to baby through the placenta (transplacental transmission).

On the same day (14 July 2020), a different journal, eLife, also carried research on vertical transmission of COVID-19. Here’s what the team, led by Dr Roberto Romero of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), US, found:

• First, the placenta has very few ACE2 receptors and very low levels of an enzyme called TMPRSS2. Now, we know from previous research that SARS-CoV-2 binds with ACE2 receptors in the lungs and uses this enzyme to enter healthy cells in the lungs, heart and blood vessels and take over all the cells’ resources. (Read more: What are ACE2 receptors and what do they have to do with COVID-19?)
• Second, they also found certain molecules in the placenta that may, in the absence of ACE2, be the gateway for this virus to enter: the CD147 receptor and two enzymes called cathepsin L and furin.
• Third and last, the researchers found that compared with Zika virus and cytomegalovirus infection, COVID-19 poses a much lower risk of transmission from mother-to-foetus.

The question of whether or not a pregnant COVID-19 patient can spread the virus to her baby is an important one—this research answers some questions even as it raises others.

That said, it is obviously heartening to know that the risk of COVID-19 transmission from expecting mom to the child is low. Further, now that we know that it can happen, and possibly how it happens, we may be able to do something prevent it. After all, the world over, expecting moms who have HIV/AIDS or hepatitis B are also able to deliver perfectly healthy children when doctors know the risks and work around them. What’s to say they can’t do the same for COVID-19, possibly soon.