Eighteen studies were excluded for the following reasons: two studies had a lack of relevant data [21,22], one study used both lactoferrin and probiotics [23], two study used both prebiotics and probiotics [24,25], five studies did not assess the NEC outcomes [26–30], the full text could not be extracted in four studies [31–34], one study was a report of additional data from a previous paper [35], and three trials were conducted before 2000 [36–38]. The gene discussed is LTF; the disease is necrotizing enterocolitis.