TNF and fetal growth restriction: Similar to our study, Niu et al. [27] reported that weaned piglets with IUGR had a higher IL-1β, IL-6, and TNF-α concentrations than NBW weaned piglets; Yan et al. [36] showed that pigs in the IUGR group had a higher mRNA expression of TNF-α, IL-6, and IFN-γ than NBW pigs; Huang et al. [56] demonstrated that piglets with IUGR have increased TNF-α and IL-6 level at birth, and Wang et al. [57] also showed that the mRNA expression of TNF-α in IUGR piglets was higher than that in NBW piglets.