IL1B and chorioamnionitis: Retinal vascularized surface area during the first postnatal week was reduced in animals subjected to IL-1β-induced chorioamnionitis (consistent with previous reports53) (Fig. 4A,B), but by Pt 8 retinal surface was fully vascularized in all groups as vessels reached the periphery (Fig. 4C); concordantly, Il1b expression was only marginally increased at Pt 8 (p < 0.06 vs sham-treated; Suppl.