NRP2 and cytomegalovirus infection: As CMV and ZIKV were commonly studied that can be transmitted vertically and cause fetal complications, such as microcephaly, multiorgan disease, congenital malformations, and intrauterine growth restriction (Schwartz, 2017), so firstly, we examined the expression levels of several CMV infection-associated factors (NRP2, PDGFRA) and ZIKV infection-associated factors (AXL, CD209) to investigate whether there is correlation between the expression levels of infection-associated factors and the ability of viruses infecting the placenta and fetus.