Doctors in France have reported what they believe to be the first proven case of Covid-19 being passed on from a pregnant woman to her baby in the womb. The newborn boy developed inflammation in the brain within days of being born, a condition brought on after the virus crossed the placenta and established an infection prior to birth. He has since made a good recovery. The case study, published in Nature Communications, follows the birth of a number of babies with Covid-19 who doctors suspect contracted the virus in the womb. Until now, they have not been able to rule out the possibility that the babies were infected during or soon after delivery. “Unfortunately there is no doubt about the transmission in this case,” said Daniele De Luca, medical director of paediatrics and neonatal critical care at the Antoine Béclère hospital in Paris. “Clinicians must be aware that this may happen. It’s not common, that’s for sure, but it may happen and it must be considered in the clinical workout.” The 23-year-old mother was admitted to the hospital on 24 March with a fever and severe cough after contracting coronavirus late in the third trimester. She tested positive for Covid-19 shortly her arrival. Three days after the woman was admitted, monitoring of the baby revealed signs of distress and doctors performed an emergency caesarean with the mother under general anaesthetic. The baby was immediately isolated in a neonatal intensive care unit and intubated because he was affected by the general anaesthetic. Tests on the baby’s blood and fluid extracted from the lungs revealed Covid-19 infection but ruled out other viral, bacterial and fungal infections. More extensive tests revealed that the virus had spread from the mother’s blood into the placenta, where it replicated and caused inflammation, and on to the baby. “The reason this has not been demonstrated before is that you need a lot of samples,” said De Luca. “You need the maternal blood, the newborn blood, the cord blood, the placenta, the amniotic fluid, and it’s extremely difficult to get all these samples in a pandemic with emergencies all around. “There have been some suspected cases, but they remain suspected because nobody had the opportunity to test all of this and check the pathology of the placenta.” The highest levels of virus were found in the placenta, which is rich in the same receptors found in the lungs that the virus uses to invade human cells. While the baby seemed healthy at first, on day three he became irritable and started feeding badly. He developed muscle spasms that made his head, neck and back arch backwards, a neurological symptom seen in some meningitis cases. MRI scans subsequently revealed signs of gliosis, a side effect of neurological injury, which can lead to scarring in the brain. At the time the boy was delivered, there was no clinical guidance on how to treat Covid-19 babies. The doctors considered administering remdesivir, an antiviral drug, but since the baby was recovering gradually without help, no specific medication was given. De Luca said a recent follow-up scan was “almost normal”. “You can see the glass as half empty or half full. The bad news is that in this case history, the virus is attacking the baby, reaching the baby and causing symptoms. The good news is that at the end of the day, the baby very much recovered. The baby is clinically fine,” he said. “Pregnant women should be reassured,” De Luca added. “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.” Asked if pregnant women should be particularly vigilant about social distancing and washing their hands, to reduce their risk of infection, De Luca said: “This is very much common sense and important whether you are pregnant or not.” Andrew Shennan, professor of obstetrics at King’s College London, said it was rare for mothers to pass Covid-19 on to their babies. “In 244 live born babies of infected mothers in the UK, 95% had no sign of the virus, and outcomes are similar to non-infected babies,” he said. “Women can remain reassured that pregnancy is not a significant risk factor for them or their babies with Coivd-19.”