Fecal Microbiota Transplantation (FMT) as a Prophylaxis of Necrotizing Enterocolitis (NEC)—Protocol for a Safety Study

<b>Background/Objectives</b>: Necrotizing enterocolitis (NEC) is an inflammatory disease with an incidence of about one in 1000 live births, much higher in premature and low birth weight newborns. Intestinal dysbiosis is an important element in the pathogenesis of NEC, and for this reason, experimental models have been used to administer fecal microbiota transplants (FMTs) for prophylaxis and treatment of NEC with very satisfactory results. The primary endpoint of the study is safety, defined as the incidence of adverse events (AEs) and serious adverse events (SAEs) occurring from the time of intervention until hospital discharge, classified according to severity and assessed for relatedness to the intervention. <b>Methods</b>: This prospective, single-arm, open-label clinical study will include 20 infants born between 24 0/7 and 36 6/7 weeks of gestation. FMTs will be administered twice as a deep rectal infusion via a Foley catheter. The donors of the material from which the FMT will be prepared will be women in the third trimester of pregnancy. The safety of the therapy will be assessed by comparison with a control group, i.e., 20 patients who will meet the same inclusion criteria and will not meet any of the exclusion criteria, subject to the same hospital observation but without undergoing any medical/therapeutic intervention other than the collection of biological material. <b>Discussion</b>: The study will provide data on the safety and initial efficacy of FMT in this group of patients, which will allow for further research into the use of this method in the prevention of infections and NEC. Ethics: The study protocol was approved by the Bioethics Committee of the Medical University of Warsaw, Warsaw, Poland (KB/52/2025). All procedures will follow the principles of the Declaration of Helsinki. The results of the study will be submitted for knowledge translation in peer-reviewed journals and presented at national and international pediatric society conferences. Clinical Trial Registration: The study is registered at ClinicalTrials.gov: ID: NCT06333405.