Researchers on Tuesday reported strong evidence that the coronavirus can be transmitted from a pregnant woman to a fetus.
A baby born in a Paris hospital in March to a mother with Covid-19 tested positive for the virus and developed symptoms of inflammation in her brain, said Dr. Daniele De Luca, who led the research team and is head of the pediatrics division. and neonatal critical care in the Paris-Saclay university hospitals. The baby, now more than 3 months old, recovered without treatment and is “much better, almost clinically normal,” said Dr. De Luca, adding that the mother, who needed oxygen during delivery, is healthy.
Dr. De Luca said the virus appeared to have been transmitted through the 23-year-old mother’s placenta.
Since the pandemic began, there have been isolated cases of newborns testing positive for coronavirus, but there has not been enough evidence to rule out the possibility of the mother infecting babies after birth, experts said. A recently published case in Texas of a newborn who tested positive for Covid-19 and had mild respiratory symptoms provided more compelling evidence that transmission of the virus can occur during pregnancy.
In the Paris case, Dr. De Luca said, the team was able to analyze the placenta, amniotic fluid, umbilical cord blood, and mother and baby blood.
Tests indicated that “the virus reaches the placenta and replicates there,” said Dr. De Luca. It can then be transmitted to a fetus, who “may become infected and have symptoms similar to those of adult Covid-19 patients.”
A case study was published Tuesday in the journal Nature Communications.
Dr. Yoel Sadovsky, executive director of the University of Pittsburgh Magee-Womens Research Institute, who was not involved in the study, said he thought the placental transmission claim was “quite compelling.” He said the relatively high levels of the coronavirus found in the placenta and increasing levels of the virus in the baby and evidence of placental inflammation, along with the baby’s symptoms, “are all consistent with SARS-CoV-2 infection.”
Still, Dr. Sadovsky said, it is important to note that cases of possible coronavirus transmission in the womb appear to be extremely rare. With other viruses, such as zika and rubella, infection and placental transmission are much more common, he said. With the coronavirus, he said, “we are trying to understand the opposite: what underlies the relative protection of the fetus and the placenta?”
Another study published Tuesday in eLife, an online research journal, may help answer that question. He found that while cells in the placenta had many of the receptor proteins that allow viruses to spread, there was only evidence of “negligible” amounts of a key cell-surface receptor and an enzyme known to be involved in allow the coronavirus to enter cells and replicate. The study was led by Dr. Robert Romero, head of the perinatology research arm at Eunice Kennedy Shriver National Institute of Child Health and Human Development.
The report by doctors in Paris said the woman was 35 weeks pregnant when she arrived at the hospital with a fever and cough that developed a couple of days earlier in what was a healthy pregnancy. She tested positive for the coronavirus. After three days, monitoring of the fetal heart indicated signs of distress, and the baby was delivered by emergency caesarean section.
The baby was placed in the neonatal intensive care unit and connected to a ventilator for approximately six hours, the authors reported. He seemed fine, but on his third day he became irritable, had trouble feeding, and experienced muscle spasms and stiffness.
A brain scan showed some white matter injury, which Dr. De Luca said resembled symptoms of meningitis or inflammation in the brain. He tested negative for other viruses or bacterial infections that could have caused such symptoms, while tests of his blood and fluid from his lungs tested positive for coronavirus infection, the authors said. The baby gradually recovered and left the hospital after 18 days.
The authors said that the highest levels of the coronavirus were found in the placenta, higher than those of the amniotic fluid and in the blood of the mother and baby, which according to Dr. De Luca suggested that the virus could replicate in the placenta. cells.
Dr. De Luca, who is also the president-elect of the European Society for Neonatal and Pediatric Intensive Care, said his team was analyzing other suspected cases of placental transmission of the coronavirus.
“This will be useful for physicians and policy makers to monitor pregnant women, monitor newborns, and reduce the risk of mother-to-newborn viral transmission,” he said, adding: “The good news is that the baby recovered spontaneously and gradually despite all this, and this confirms that the disease is milder in early childhood. “
