In macaques:

"The pattern of infection observed suggests that ZIKV vertically transmits not through a transplacental route but through a paraplacental route by infecting the chorionic membrane, the outer layer of the fetal membranes. This finding is significant because it challenges the assumption that vertical transmission occurs exclusively across the placenta."

https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1011274