S100a8, S100a9, Il1b, and Mmp8 have been strongly associated with fetal inflammatory response syndrome (FIRS), preterm labor, and chorioamnionitis in preterm infants (Kallapur et al., 2013; Holmstrom et al., 2019; Golubinskaya et al., 2020), further supporting our rat model using IA LPS injections to simulate IAI and a FIRS-like response. Here, S100A9 is linked to chorioamnionitis.