Viral infection, proliferation, and hyperplasia of Hofbauer cells and absence of inflammation characterize the placental pathology of fetuses with congenital Zika virus infection.

Inflammatory abnormalities of the placenta are not a component of vertical transmission of the Zika virus. The major placental response in second and third trimester transplacental Zika virus infection is proliferation and hyperplasia of Hofbauer cells, which also demonstrate viral infection.