Doctors say a baby boy caught Covid-19 in the womb after contracting the infection from his mother, in what is thought to be the first proven case of in utero transmission. 

Fortunately, the mother and baby are now doing well, although both were fairly sick before their recovery. 

Reported in the journal Nature Communications, doctors at Antoine Béclère Hospital in the suburbs of Paris explain the 23-year-old mother was admitted to the hospital in March 2020 when she was late into the third trimester of pregnancy. After showing symptoms including a sky-high fever and a nasty cough, she tested positive for SARS-CoV-2, the virus responsible for Covid-19. 

Just a few days after being admitted to hospital, doctors noticed that her baby was showing signs of distress so decided to carry out an emergency cesarean section. The child was born and immediately moved to an isolated neonatal intensive care unit. 

Tests on the baby’s blood and fluid extracted from the lungs revealed he also had a Covid-19 infection. While he appeared healthy for the first three days of life, the baby started to become irritable and had difficulty feeding, which the report says is “consistent with neurological signs and symptoms of Covid-19.” The baby went on to recover without the need for medication and his follow-up scans showed the all-clear. 

According to the study authors, this is the first confirmed case of a baby being infected with Covid-19 in utero via transplacental transmission. Italian researchers have also presented two cases that appear to show Covid-19 transmission from mother to child during pregnancy, although their study is yet to be peer-reviewed. Doctors have previously reported cases of newborn babies testing positive for Covid-19, although it didn’t appear the new coronavirus was transmitted in the womb through the placenta. 

“This is a very detailed and well-characterized case report showing very likely transplacental transmission of the SARS-CoV-2 virus,” commented Professor Christoph Lees, Professor of Obstetrics at Imperial College London, who was not involved in the study.

However, some other medical experts are not totally convinced by this claim.

“This case study does not provide strong evidence for transmission of SARS-CoV-2 via the placenta,” argues Professor Alexander Heazell, professor of obstetrics and director of the Tommy's Maternal and Fetal Health Research Centre at the University of Manchester. 

“[The report] only shows presence of the virus within the outer layer of the placenta (the syncytiotrophoblast), there is no evidence of the virus in the next layer of cells (the stromal cells). Therefore, there is evidence that the placenta itself may be infected, but no evidence that the virus has successfully passed through the placenta to infect the fetus.” 

Though there does appear to be growing evidence of the possibility of in utero transmission, it appears the risk of newborn babies contracting Covid-19 is still low. Although it’s a problem that clinicians should be aware of, it’s not something that should keep expecting parents up at night.

“Among the many thousands of babies born to mothers with SARS-CoV-2 infection, very few have been reported to also have a positive test for SARS-CoV-2 – around 1 to 2 percent. As in this report, most babies do not appear to become severely unwell,” said Professor Marian Knight, Professor of Maternal and Child Population Health at the University of Oxford.