A study of 101 newborns in New York City hospitals published yesterday in JAMA Pediatrics found no evidence of transmission of COVID-19 from infected mothers to their babies when basic infection-control protocols were followed, while a small Italian study suggests that coronavirus genetic material may pass from mother to fetus in utero.
No signs or symptoms in infants
The first study involved obtaining 141 test results from the newborns, including one set of twins, admitted to two hospitals at a large academic medical center in New York City from Mar 13 to Apr 24.
Seventy-six mothers, who were required to wear face coverings, stayed with their babies in private rooms, while mothers of the 19 newborns admitted to the neonatal intensive unit weren't permitted to visit for 14 days, and 6 mom-baby pairs were separated because the mothers were in intensive care.
Delayed infant bathing and direct breastfeeding after hand washing and breast washing were both encouraged for babies rooming with their mothers, and the newborns rested in protective cribs 6 feet away from their mothers' beds.
Two newborns had positive COVID-19 test results but no signs or symptoms; one of them wasn't retested, and the other was negative on retesting. Follow-up of 58 of the infants at 3 to 25 days old found that all the newborns remained well, and none had evidence of COVID-19 infection, including six with negative results on retesting.
Moms severely or critically ill with coronavirus gave birth about 1 week earlier than those with asymptomatic or mild infections (median gestational age, 37.9 weeks vs 39.1 weeks), and their babies were more likely to need phototherapy to treat jaundice (30% vs 7%).
Original recommendations may not be necessary
The authors said that breast milk may help protect newborns against the novel coronavirus, and maternal vaginal secretions and skin-to-skin contact are known to foster neonatal immune responses. Delayed bathing can increase the likelihood of exclusive breastfeeding and guard against hypothermia and dangerously low blood glucose.
Recommendations to separate infected moms from their babies and discourage breastfeeding were made in the absence of data on rates of mother-to-baby transmission and were based on experience with mother-newborn transmission of other infectious diseases, lead author Dani Dumitriu, MD, PhD, of New York-Presbyterian Morgan Stanley Children's Hospital, said in a Columbia University Irving Medical Center press release.
"But some of the recommendations conflict with what we know about the developmental benefits of early breastfeeding and skin-to-skin contact," she said. "Our study offers further evidence that these measures may not be necessary for healthy newborns with SARS-CoV-2-positive moms," she added, referring to the virus that causes COVID-19.
In an editorial in the same journal, David Kimberlin, MD, of the University of Alabama at Birmingham, and Karen Puopolo, MD, PhD, of the University of Pennsylvania in Philadelphia, said that initially conservative recommendations for the management of newborns of mothers infected with COVID-19 have evolved with new knowledge. At the same time, the difficulties of separating mothers and newborns have become more apparent.
"The balance between these risks has greater clarity now and will be considered when revisions are made to neonatal management guidance," they wrote. "This is exactly how the scientific method is supposed to work. Despite the many horrors of the past months, we can draw solace from the knowledge that scientific processes that have worked in the past are working now and will continue to serve us as we move together into an uncertain future."
Genetic material, not infectious virus
The second study, published yesterday in Nature, suggests that RNA from SARS-CoV-2 may be transmitted from infected mothers to their babies in utero, but its authors did note detect live virus.
University of Milan researchers studying 31 mothers infected with COVID-19 and their newborns identified SARS-CoV-2 RNA in blood from one umbilical cord, two at-term placentas, two maternal plasma samples, one vaginal mucosa sample, and one breast milk sample. They also detected specific anti-coronavirus immunoglobulin M and G antibodies in one umbilical cord blood sample and one milk sample.
All of the pregnancies except one were full term, and all except two newborns were breastfed. Two newborns tested positive for COVID-19 on delivery but never had signs or symptoms. One of them could have had a congenital infection because coronavirus RNA was detected in the infant's nose-throat swab and in a placenta sample and umbilical cord plasma. The other, in contrast, could have been infected during birth because of positive nose-throat swabs at birth but not 24 to 48 hours later and the presence of SARS-CoV-2 antibodies in the umbilical cord plasma.
Four mothers were severely ill, and emergency delivery was needed for three of them because of maternal respiratory distress. One mother was admitted to the intensive care unit after delivery and underwent mechanical ventilation for 11 days.
"Together, these data support the hypothesis that in utero SARS-CoV-2 vertical transmission, while low, is possible," the authors wrote. "These results might help defining proper obstetric management of COVID-19 pregnant women, or putative indications for mode and timing of delivery."