Newborns and babies have so far seemed to be largely unaffected by the coronavirus, but three new studies suggest that the virus may reach the fetus in utero.

Even in these studies, the newborns seemed only mildly affected, if at all — which is reassuring, experts said. And the studies are small and inconclusive on whether the virus does truly breach the placenta.

“I don’t look at this and think coronaviruses must cross across the placenta,” said Dr. Carolyn Coyne of the University of Pittsburgh, who studies the placenta as a barrier to viruses. She was not involved in the new work.

Still, the studies merit concern, she said, because if the virus does get through the placental barrier, it may pose a risk to the fetus earlier in gestation, when the fetal brain is most vulnerable.