IL1B and infection: After exposure to a prenatal infection/inflammation, the predominantly amoeboid microglia in the fetal brain can potentially remain in this state into postnatal life (Bilbo and Schwarz, 2009; Hagberg et al., 2012), possibly exposing the fetal and postnatal brain to over-expression of pro-inflammatory cytokines, such as IL-1β, IL-6 and TNF-α [reviewed in Jonakait (1997); Bilbo and Schwarz (2009)].