Studies have already shown that there is a relevant association between BPD development and VEGFA activity in preterm infants.[29,30] VFGFA was shown to play vital roles in the repair of vascular lung, and the lack of VEGFA activity could lead to an impairing lung microvascular development in fetus.[31] IL6 expression was found to be increased with the histologic severity of chorioamnionitis as well.[32]. This evidence concerns the gene IL6 and chorioamnionitis.