By Julie Steenhuysen
CHICAGO (Reuters) - Researchers at the University of Miami reported on Thursday what they believe are the first two confirmed cases in which the SARS-CoV-2 virus crossed a mother's placenta and caused brain damage in the infants they were carrying.
Doctors previously had suspected this was possible, but until now, there was no direct evidence of COVID-19 in a mother's placenta or an infant's brain, the team told reporters at a news briefing.
The babies were born to young mothers who tested positive for the virus during their second trimester at the height of the pandemic's Delta wave in 2020, before vaccines were available. The case studies were published in the journal Pediatrics.
Several viruses are known to be capable of crossing the placenta and causing fetal brain damage, including Cytomegalovirus, Rubella, HIV and Zika. The SARS-CoV-2 virus has been detected in adult brain tissue, and some experts had suspected it could also damage fetal brain tissue.
"This is the first time that we've been able to demonstrate the virus in a fetal organ with transplacental passage," Dr. Michael Paidas, chair of obstetrics and gynecology at the University of Miami, told the briefing. "That's why we think this is so important."
The newborns had seizures from the first day of life. However, unlike Zika, the babies were not born with microcephaly, a condition marked by small head size. Instead, microcephaly developed over time as their brains stopped growing at a normal rate, the team said.
Both infants had severe developmental delays. One of the children died at 13 months, and the other was in hospice care, the team said.
Neither of the infants tested positive for the SARS-CoV-2 virus, but they did have high levels of COVID antibodies in their blood, Dr. Merline Benny, a neonatologist and assistant professor of pediatrics at the University of Miami, told the briefing. She said that suggests the virus crossed from the mother, through the placenta and to the baby.
The team found evidence of the virus in both mothers' placentas. An autopsy of the child's brain who died revealed COVID virus in the brain, suggesting direct infection caused the injuries, Benny said.
As for the mothers, although both tested positive for the virus, one woman had only mild symptoms and carried the baby full term while the other was so sick that doctors had to deliver the baby at 32 weeks of gestation.
Dr. Shahnaz Duara, an obstetrician and gynecologist at the University of Miami, said she believed the cases were rare, but urged women who had been infected during their pregnancies to inform their children's pediatricians to check for developmental delays.
"We know that things can be fairly subtle up to seven or eight years of age, until kids go to school," she said.
The team also urged women who were considering pregnancy to get vaccinated against COVID, and said pregnant women should consider vaccination.
It was not yet clear whether the injuries caused during pregnancy were unique to the Delta variant of SARS-CoV-2 or could occur with Omicron-related variants.