A small study strengthens evidence that a pregnant woman infected with the coronavirus might be able to spread it to her fetus.

Researchers from Italy said Thursday that they studied 31 women with COVID-19 who delivered babies in March and April. They found signs of the virus in several samples of umbilical cord blood, the placenta and, in one case, breast milk.

Women shouldn't panic. This doesn't mean there's viable virus in those places and "it's too early to make guidelines" or to change care, said the study leader, Dr. Claudio Fenizia, an immunology specialist at the University of Milan.

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