COVID-19 mild for newborns, but in utero transmission is a possibility

Getty Images/iStockphoto
Getty Images/iStockphoto 

Newborn babies infected with the coronavirus in China experienced only mild symptoms finds new research, which also highlighted that mother-to-baby transmission cannot be ruled out.

As part of the study, published in European Respiratory JournalDr Zhi-Jiang Zhang and colleagues at Wuhan University in China, identified four newborn babies who were diagnosed with COVID-19 prior to 13 March. All four were born to mothers with COVID-19 and all were delivered by C-section.

Two of the babies had a fever, one had shortness of breath, one had a cough and one had no noticeable symptoms. The newborns ranged in age from 30 hours to 17 days old. None required intensive unit care or mechanical ventilation and no babies had any severe complications from the coronavirus.

Of the four mothers, three showed symptoms prior to delivery while one displayed symptoms post birth.

"It is encouraging that newborn babies and infants appear to be less vulnerable to SARS-CoV-2," the authors write. "On the other hand, mild or no symptoms in the youngest make it difficult to detect and prevent further transmission."

While the news around the health impacts of COVID-19 on our youngests patients is positive, the authors say their research supports "intrauterine transmission potential" for a number of reasons.

All four newborn babies were delivered via C-section, so the possibility of mother-to-child transmission by vaginal delivery was excluded. While one baby had contact with an infected visitor, all three other babies were in isolation when symptoms occurred. Only one child was breastfed and the time between birth and diagnosis was limited, ranging between 30 hours and five days. "Taken together, the chance of infection through ways other than intrauterine transmission is deemed to be low," they write.

The authors do caution, however, that other explanations are also possible. Hospital-acquired infection cannot be ruled out although all necessary safety precautions were used. In addition, the researchers argue that SARS, another coronavirus with similar genome sequence, was not found to be vertically transmitted.

To date, the limited information available on transmission has been mixed. While one previous study of six pregnant mothers published in The Lancet found no evidence of vertical transmission, another more recent study, published in JAMA Pediatrics on March 26, noted that vertical maternal-fetal transmission could not be discounted in their cohort of three infected newborns.  

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 "COVID-19 is highly contagious and our study suggests that intrauterine transmission cannot be ruled out, but that the prognosis is good for both pregnant women and newborn babies," concludes lead author Dr Zhang.

Professor Tobias Welte, an infections expert from the European Respiratory Society who was not involved in the study said, "It's important to protect pregnant women and newborn babies against infection. It's also important that any cases of COVID-19 in newborns are picked up, monitored and treated quickly and carefully. At this stage we still do not know whether there are any longer-term consequences of infection."

Current advice from The Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG) notes, "There have been a handful of very recent case reports suggesting that the virus may pass from the mother to the baby (vertical transmission). However, this is very early, preliminary data and has not been confirmed."

According to RANZCOG, "Woman should remain reassured, given our extensive knowledge of the impact of the effect of other respiratory viruses, that there is currently no evidence that COVID-19 will harm your baby or cause abnormalities."