A new study by scientists in Miami suggests that, in rare instances, a pregnant mother with COVID-19 can transmit the virus to the baby via the placenta — which can have serious consequences for the infants.
Most pregnant people who contract COVID-19 go on to have healthy babies who leave the hospital without complications.
But a new peer-reviewed study by researchers at the University of Miami Health System and Miller School of Medicine, published in the journal Pediatrics, highlighted two cases in which the mothers — both Latina, in their early 20s and living in South Florida — contracted COVID-19 in their second trimester of pregnancy and their babies suffered from brain damage that could be linked to the condition.
Neither of these two babies tested positive for the disease, though COVID-19 antibodies were found in the blood, "which suggests that the COVID antibodies must have crossed from the mother through the placenta to the baby," Benny said.
Both babies had seizures that developed from the first day of life, "and they had profound low [muscle] tone in their clinical exam, what we call hypotonia. As they grew, they had a very small head circumference. The brain imaging on these two babies showed significant brain atrophy."
As the first reported cases of transmission of this kind, the researchers say they represent a significant finding, but one which is extremely rare and requires further study. They also point out that the pregnancies took place before the availability of vaccines.
"This is not to panic the population … We do think if you’ve had COVID in pregnancy, [it's] something you should tell your pediatrician, and maybe those babies need a little closer follow up."Dr. Shahnaz Duara, professor of pediatric medicine at the University of Miami Miller School of Medicine
Dr. Shahnaz Duara, professor of pediatrics at the University of Miami Miller School of Medicine
Unlike with the Zika virus, for instance, which causes brain injury in babies before birth, in these two cases they were not born with microcephaly.
The researchers explained that the mothers had different COVID-19 experiences. One had a very severe COVID-19 presentation, spent about a month in the intensive care unit and doctors decided to deliver the baby at 32 weeks so they could care for the mom. In contrast, the other patient had a light case, nearly asymptomatic around 27 weeks or so and delivered full term, close to her delivery date.
One of the two babies died at 13 months. An autopsy revealed traces of COVID-19 in the child's brain, which raises the possibility that the SARS-CoV-2 infection of the brain could have directly contributed to the ongoing injury. The other baby was in hospice at the time that the researchers submitted their manuscript.
More research and a greater understanding needed
"This is not to panic the population," said Dr. Shahnaz Duara, professor of pediatrics at the University of Miami Miller School of Medicine, the medical director of the NICU at Holtz Children’s Hospital, and senior author on the study.
"Since the start of the pandemic, we have had nearly 700 mother-infant pairs in the Jackson hospital who were admitted, and all these mothers who were COVID positive — majority of them were asymptomatic, and even the infants, majority of them were very healthy after delivery and left the hospital without any complications," said Dr. Merline Benny, assistant professor of pediatrics, a neonatologist and first author on the paper.
The team hopes their findings will contribute to a greater understanding of the effects of COVID-19 on newborns and children — especially among doctors.
"We do think if you’ve had COVID in pregnancy, [it's] something you should tell your pediatrician, and maybe those babies need a little closer follow up because we know that things can be fairly subtle until kids start going to school," Duara added.
Neither mother was vaccinated because COVID-19 vaccines were not available at that point in 2020 during the pandemic, 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 and Jackson’s chief of service for obstetrics and gynecology.
"We're on a learning curve about the detection of the virus and the organs," Paidas said. "In terms of the the microcephaly antenatally, we're not seeing brain malformations in COVID positive patients, unlike other viral conditions that we've had recently.
"So we had to take the time to actually go through and document the presence of the virus in the fetal organ. This is the first time that we've been able to demonstrate a newborn ... with transplacental passage. So that's why we think this is so important."
The researchers said they had not heard about passage of COVID-19 through the placenta before their reporting.
Vaccines provide protection, said Paidas, who encourages people to get vaccinated against the coronavirus that causes COVID-19. He and his colleagues said, during a press briefing on April 6, that not much is known about the time of a coronavirus (SARS-CoV-2) infection and the outcomes on the baby.
"So we need more research and we need more patient engagement in the clinical trial arena," Paidas said. "And finally, we need a longer term follow up."
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