Researchers reported no cases of viral transmission among 120 babies born to 116 Covid-positive mothers, even when both shared a room and the mothers breastfed.
Still, precautions were taken: Babies remained in enclosed cribs, six feet apart from their mothers, except while breastfeeding. Mothers were also required to wear surgical masks when handling their child and followed proper hand and breast washing procedures.
The study observed mothers and their babies at three New York City hospitals between March 22 and May 17. All babies included in the study were tested for Covid-19 via a nasal swab within 24 hours after birth. After, researchers conducted follow up exams and tests.
Of the original 120 babies, 82 completed a follow up five to seven days after birth. The majority, 68 babies, had roomed with their mothers and 64 were still breastfed. Seventy-nine of these babies were tested again at five to seven days, and 72 were tested two weeks after birth.
None of the results were positive, and none of the babies showed Covid-19 symptoms, the team at Weill Cornell Medicine-New York Presbyterian children’s hospital reported.
However, the researchers noted that blood, fecal and urine Covid-19 tests had not been approved at the time of the study. If a baby was infected in the womb, the nasal swab test might not have detected the virus. The researchers also relied on what the mothers reported themselves about their hand hygiene and mask usage.
In addition, a third of the families did not come back for follow-up visits, and the researchers said fear of leaving home or of using public transportation to attend appointments might have been the reason.
The researchers noted larger studies are needed before definitive recommendations can be made.
“Data on the risk of Covid-19 transmission during pregnancy or while breastfeeding are limited to a small number of case studies,” said study lead Dr. Christine Salvatore, chief of the division of pediatric infectious diseases at New York – Presbyterian/Weill Cornell Medical Center, in a statement.
“Consequently, guidelines for pregnant women and new mothers vary. We hope our study will provide some reassurance to new mothers that the risk of them passing Covid-19 to their babies is very low,” Salvatore said.
“However, larger studies are needed to better understand the risks of transmission from mother to child.”
In April, the AAP had recommended temporary separation of newborn babies from infected mothers, based on limited data from China. There, doctors universally separated infected mothers and newborns after birth and isolated them for 14 days.
“What we now know is the risk of the newborn becoming infected around the time of birth is low when safety precautions are taken to protect the baby,” lead author Dr. Karen Puopolo, who is the medical director of newborn care at Children’s Hospital of Philadelphia.
“In fact, the risk in the short-term appears to be no greater if mother and infant room-in together using infection control measures compared to physical separation of the infant in a room separate from the mother,” Puopolo said in a statement.
The updated pediatrician-issued guidance has not recommended against breastfeeding. It cites several studies that detected genetic evidence of coronavirus in breast milk, but it is unclear whether the virus in the milk was viable and could affect a baby or whether protective antibodies were secreted in milk as well.
The World Health Organization, however, says the benefits provided by breastfeeding “substantially outweigh” the potential transmission risks of Covid-19 from mothers to infants.
The US Centers for Disease Control and Prevention reported 12,969 Covid-19 cases among pregnant women between January 22 and July 21, of which 35 women died.
Current data suggests between 2% and 5% of newborns tested positive for coronavirus within the first 24 to 96 hours of life if born to a mother with Covid-19, according to the American Academy of Pediatrics.
Though strong evidence for Covid-19 transmission from a mother to her unborn child was reported last week in Nature Communications, researchers say coronavirus infection in the womb is rare.