According to a study, the coronavirus is transmissible from pregnant women to their babies. - SUPERSTOCK / SUPERSTOCK / SIPA

Mothers positive for Covid-19 can transmit the virus to their unborn children, according to "solid evidence" released Thursday by researchers whose work could have an impact on the protection of pregnant women during the pandemic.

Although there have only been isolated cases of babies infected with the coronavirus, these results show the strongest link to date on mother-to-child transmission.

The virus found in the placenta and breast milk

Researchers studied 31 infected hospitalized pregnant women and found the virus in a full-term placenta, the umbilical cord, a woman's vagina and breast milk. They also identified specific Covid-19 antibodies in umbilical cords in several women as well as in milk samples.

Claudio Fenizia, of the University of Milan and lead author of the study, said the results "strongly suggest" that in utero transmission is possible. "Given the number of people infected worldwide, the number of women likely to be affected by this phenomenon could be potentially very high," he said.

None of the infants born during the study period were positive for Covid-19, the researcher said. "Although in utero transmission seems possible, it is too early to clearly assess the risk and the potential consequences," he said.

A specific inflammatory response

The World Health Organization (WHO) said last month that mothers infected with the new coronavirus should continue to breastfeed. "We know that children are at relatively low risk for Covid-19, but are at high risk for many other diseases and conditions that breastfeeding prevents," said WHO Director-General Tedros Adhanom Ghebreyesus.

Among other findings, the team identified a specific inflammatory response triggered by Covid-19 in these women in the blood plasma of the placenta and umbilical cord. The women studied were all in their third trimester of pregnancy, said the researcher adding that more research is in progress among women positive for Covid-19 in the early stages of pregnancy. "Our study aims to raise awareness and invite the scientific community to consider pregnancy in HIV-positive women as an urgent subject to further characterize and dissect," said Professor Fenizia.

"I believe that promoting prevention is the surest advice we could possibly give to these patients right now."

The study was made public at the 23rd International AIDS Conference held this week, for the first time online due to the Covid-19 pandemic.

  • Pregnancy
  • Covid 19
  • Baby
  • Coronavirus
  • Health