Chorioamnionitis which results from microbial invasion of the amniotic cavity is the most frequent cause of preterm birth. Chorioamnionitis is associated with an increased risk of early-onset sepsis but the mechanisms underlying this association remain largely unknown. We hypothesize that developmental alterations of fetal organs and the immune system in the course of chorioamnionitis determine the risk of development of early onset sepsis. The purpose of this review is therefore to summarize the consequences of chorioamnionitis on fetal development and speculate how those antenatal changes might predispose to early onset sepsis.