They assessed 31 women with COVID-19 who delivered babies in March and April, and found signs of the virus in several samples of umbilical cord blood and the placenta and one sample of breast milk, the Associated Press reported.
The research was presented at a medical conference being held online.
Still, pregnant women shouldn't be alarmed, said study leader Dr. Claudio Fenizia, an immunology specialist at the University of Milan.
The findings don't mean there's viable coronavirus in the samples and "it's too early to make guidelines" or to make changes in the care of pregnant women, according to Fenizia, the AP reported.
But more research is needed, especially in women who are infected earlier in their pregnancies, Fenizia said.