Pregnant women infected with COVID-19 may pass on the disease-causing virus to their baby through the placenta, researchers in France suggest.

In their study, published in Nature Communications, the authors describe the case of a newborn child which presented with SARS-CoV-2 infection shortly after birth and subsequently suffered neurological conditions consistent with symptoms seen in adults with COVID-19.

Through analysis of the blood of mother and child as well as placenta and amniotic fluid, they give strong evidence for the virus to have been transmitted by the infected mother through the placenta. Scientists hope that taken together with other case reports, this could give indications for the risk and impact of COVID-19 infections during pregnancy.

‘This case study is indeed an important addition to the existing literature,’ commented Dr Ela Chakkarapani from the University of Bristol, who was not involved in the study. ‘Data to date has been suggesting in utero transmission may be occurring and this study adds data to further support that.’

In March 2020, the pregnant woman was hospitalised in Paris with symptoms of COVID-19 and tested positive for the virus. Despite immediate isolation after being born by caesarean section, the newborn boy developed neurological symptoms quickly – including distress and muscle spasms – which mirrored COVID-19-related effects in adults. With his health improving soon after, the baby and his mother recovered and were discharged from the hospital.

The authors conclude that based on their analysis of blood, amniotic fluid and placenta, transmission of the virus via the placenta was very likely in the reported case. This adds fire to the ongoing medical debate over the likelihood of an elevated risk of coronavirus infection for expectant mothers and their children, especially in the context of placenta-transmitted disease. According to the CDC, the major source of transmission to babies is contact with respiratory droplets from mothers or other caregivers immediately after birth.

‘It remains rare for babies to become infected; in 244 live-born babies of infected mothers in the UK, 95 percent had no sign of the virus, and outcomes are similar to non-infected babies,’ commented Professor Andrew Shennan from King’s College London. ‘This report adds knowledge to a possible mechanism of transfer to the baby, i.e, via the placenta while pregnant, but women can remain reassured that pregnancy is not a significant risk factor for them or their babies with COVID-19.’

Read more: https://www.nature.com/articles/s41467-020-17436-6