Doctors in France have found the world's first recorded case of an unborn child contracting COVID-19 from their mother while inside the womb

Doctors in France have reported what they say is the first confirmed case of an unborn child contracting the coronavirus from their mother while still in the womb.

The case was the subject of a paper titled "Transplacental transmission of SARS-CoV-2 infection," published Tuesday in the peer-reviewed journal Nature Communications. Details of the paper were first reported by The Guardian.

Until now, there has been limited evidence suggesting that an unborn child could catch the coronavirus from inside the womb, but the paper's authors, from the Antoine Béclère hospital, in Paris, confirmed "transplacental transmission of SARS-CoV-2" was possible.

They said a 23-year-old woman was admitted to the hospital with a fever and cough on March 24 when she was more than 35 weeks pregnant with a boy.

A doctor holds the newborn son of a coronavirus patient at Monica Pretelini Maternal Hospital in Toluca, Mexico, on May 29, 2020. Not the case mentioned in this story.Cristopher Rogel Blanquet/Getty Images

The mother tested positive for the coronavirus, gave birth by cesarean section, and the baby was immediately taken to the natal intensive care unit.

The baby tested positive for the virus. He later recovered and was discharged 18 days later, the doctors said.

They said the baby's brain bore evidence of inflammation caused by the coronavirus, which had crossed the placenta into the baby's bloodstream. They ruled out the chance that the baby caught the virus after birth by viral or bacterial means.

"The placenta showed signs of acute and chronic intervillous inflammation consistent with the severe systemic maternal inflammatory status triggered by SARS-CoV-2 infection," the authors said.

A pregnant woman wearing a face mask walks past a mural in Hong Kong on March 23, 2020.ANTHONY WALLACE/AFP via Getty Images)

The doctors said there have been similar cases of babies being born with the coronavirus, but, until now, they had not been able to say definitively whether babies could contract the virus in utero.

A small study done on 31 women in Italy in March and April found some evidence showing that unborn babies could catch the virus from their mothers.

Three other studies published in March also found evidence that it was possible.

The doctors in France wrote, "We have demonstrated that the transplacental transmission of SARS-CoV-2 infection is possible during the last weeks of pregnancy.

"Other cases of potential perinatal transmission have recently been described, but presented several unaddressed issues," the authors said.

A pregnant woman seen during an ultrasound at a perinatal center in Tatarstan on June 5, 2020.Yegor Aleyev\TASS via Getty Images

However, Daniele De Luca, the lead author and medical director of pediatrics at the Paris hospital, told The Guardian that cases like this were very rare.

"Pregnant women should be reassured," he said. "Pregnancy is very controlled, and if you have something like this, it can be controlled. In most cases there will be no damage to the baby.

"There are many things we can do, but we can't close our eyes and say this is never going to happen." The long-term effect of the coronavirus on coronavirus-positive pregnant women and their unborn children remains unknown.