To understand if the Treg population may play a role in NEC occurrence, we performed a multiparametric flow cytometry analysis in the peripheral blood of the neonates whose samples were collected at least at both T0 and T1, to quantify the frequency of total Tregs (identified as CD127low CD25high in gated CD4 T cells) and of the highly suppressive actTreg subset (identified as FOXP3hi CD45RAlow in gated CD127low CD25high Tregs). This evidence concerns the gene CD4 and necrotizing enterocolitis.