Researchers found the coronavirus and antibodies against it in the umbilical cord blood, breast milk, placentas and vaginas of some pregnant infected women, another suggestion that the virus can be passed to fetuses and newborns, The Washington Post reports citing results of a small study released Thursday, July 9.

Just two of the infants in the sample examined by Italian researchers tested positive for the virus, and both quickly recovered. In one case, a baby tested negative two days later, an indication that the child was already producing antibodies against the virus in the womb, said Claudio Fenizia, an assistant professor of immunology at the University of Milan, who led the study.

In an interview, Fenizia said the review of 31 pregnant women is preliminary and was plagued by factors that make it too early to draw conclusions for use in the care of pregnant women infected by the virus. But, he said, “our study should be considered a ringing bell to raise awareness that [transmission] is possible.” He urged further research in the area, which is underway in some places.

The full study is not yet available. An abstract with results was released Thursday ahead of a one-day worldwide conference on covid-19 scheduled for Friday. Previous reports on a small number of infected women in China reached similar conclusions.