TAMPA, Fla. (WFLA) — Researchers at at UHealth—the University of Miami Health System and the University of Miami Miller School of Medicine—say they have found evidence that suggests pregnant women can pass COVID-19 to their babies, causing brain damage in newborns.

According to a press release, UHealth identified two cases where a COVID-19 infection breached the placenta during pregnancy and damaged the baby’s brain.

According to the study, the two infants were admitted to the Neonatal Intensive Care Unit (NICU) at Holtz Children’s Hospital, which is affiliated with the Millers School. Both babies “tested negative for the virus at birth, but had significantly elevated SARS-CoV-2 antibodies detectable in blood.”

Researchers believe “either antibodies crossed the placenta, or passage of the virus occurred and the immune response was the baby’s.”

The study said both infants had small head sizes and experienced seizures and developmental delays. One died at 13 months old. Both mothers had been infected with COVID-19 during their second trimesters, and cleared it, but one had a repeat infection during their third trimester.

Ali G. Saad, M.D., a neuropathologist examined both placentas and found changes caused by COVID-19 in both. He also observed major changes in the brain in the autopsy.

“I was struck by the unexplained severity of the loss of the white matter and the presence of features of hypoxia/ischemia in the cerebral cortex. We became suspicious that the virus, somehow, managed to breach the placental barrier to damage the central nervous system, but this had not been documented before,” said Saad, who is a Miller School professor and the director of the pediatric and perinatal pathology service at Holtz Children’s.

The study notes that both cases occurred in early 2020 before the vaccine was made available, and were rare occurrences—UM clinicians have seen hundreds of pregnant women and delivering mothers with COVID-19 positivity whose babies did not experience devastating brain injuries.

“Many women are affected by COVID-19 during pregnancy, but to see these kinds of problems in their infants at birth was clearly unusual”, said Dr. Shahnaz Duara, the medical director of the NICU at Holtz and senior author on the study. “We’re trying to understand what made these two pregnancies different, so we can direct research towards protecting vulnerable babies.”

“We need to continue our research to figure out why these two babies experienced such devastating results,” said Merline Benny, M.D., assistant professor of pediatrics, a neonatologist and first author on the paper. “Once we fully understand the causes, we can develop the most appropriate interventions.”

Neonatologists documented cases of transient lung disease and blood pressure issues in some newborns born early in the pandemic. Like the other two newborn, those babies tested negative at birth, although their mothers tested positive for the virus.

“If we saw a baby who presented this way, we would call it hypoxic ischemic encephalopathy (brain damage caused by decreased blood flow),” said Dr. Michael Paidas, professor and chair of the Department of Obstetrics, Gynecology and Reproductive Sciences at the University of Miami Miller School of Medicine. “But it wasn’t lack of blood flow to the placenta that caused this. As best we can tell, it was the viral infection.”