Necrotizing enterocolitis (NEC) is a serious intestinal disease that primarily affects premature or sick newborns, causing inflammation and tissue death in the intestines. This condition can lead to a perforation, or hole, in the intestinal wall, allowing bacteria to leak into the abdomen or bloodstream and cause life-threatening infections. While the exact cause is not fully understood, reduced blood flow to the bowel and the presence of intestinal bacteria are believed to play a role.
Newborn Vulnerabilities
Prematurity and low birth weight are among the most significant factors increasing a newborn’s susceptibility to NEC. Infants born before 37 weeks of gestation, particularly those weighing less than 2,500 grams (approximately 5.5 pounds), face a higher risk. The earlier a baby is born, the greater their likelihood of developing NEC.
Premature infants have underdeveloped digestive systems, which can struggle to adequately digest food and move it through the intestines, leading to a buildup of potentially harmful substances. Their immature immune systems are also less capable of fighting off infections, making them more vulnerable to the inflammation that can lead to NEC. The intestinal barrier, which normally prevents dangerous bacteria from entering the bloodstream, is not fully mature in preterm babies, typically developing around 26 weeks of gestation.
Blood Flow and Oxygen Factors
Conditions that compromise blood flow and oxygen supply to a newborn’s intestines significantly increase the risk of NEC. When there is insufficient oxygen, the body prioritizes blood flow to vital organs like the brain and heart, reducing circulation to the intestinal tract. This diminished blood flow can damage intestinal tissue, making it more susceptible to inflammation and necrosis.
Congenital heart defects, such as patent ductus arteriosus (PDA), can alter blood flow and contribute to NEC, even in full-term infants. Birth asphyxia, a lack of oxygen at birth, also reduces intestinal blood flow, increasing NEC risk. Other circulatory issues, including polycythemia (too many red blood cells), also increase risk.
Feeding and Gut Health Factors
Feeding practices and the development of the gut microbiome play a substantial role in influencing NEC risk. Breast milk offers a protective effect against NEC, as it contains growth factors, antibodies, and immune cells that support intestinal health and fight infection. Studies show that NEC is significantly less common in infants fed human milk compared to those receiving formula.
The gut microbiota, the community of bacteria in the intestines, is also a contributing factor. An imbalance in this microbial community, known as dysbiosis, is frequently observed in infants who develop NEC. While the exact causative pathogens remain elusive, an overgrowth of opportunistic bacteria and a reduction in overall microbial diversity have been associated with NEC development.
Medical Interventions
Certain medical interventions can increase the risk of NEC in vulnerable infants. Rapid advancement of enteral feedings, increasing volumes too quickly, has been investigated for its link to NEC, though studies show mixed results. The use of umbilical catheters, particularly umbilical arterial catheters, can affect intestinal blood flow and has been associated with NEC.
Complications such as abdominal aortic embolism linked to umbilical arterial catheters have been reported as a cause of NEC. Certain medications like indomethacin, used to close a patent ductus arteriosus, can reduce mesenteric blood flow and are associated with an increased incidence of NEC when administered postnatally. Blood transfusions have also been identified as a risk factor, with some studies indicating an increased risk of NEC within a few days following a transfusion.
Reducing the Risk
Healthcare providers employ several strategies to reduce the risk of NEC in at-risk infants. Promoting breast milk feeding is widely recommended, as human milk provides numerous protective components that support gut development and immunity. When mother’s milk is unavailable, pasteurized donor human milk is considered a safer alternative to formula.
Careful feeding protocols, including the gradual introduction and advancement of enteral feeds, are implemented to minimize stress on the immature digestive system. Standardized feeding protocols have been shown to reduce the risk of severe NEC. The judicious use of antibiotics and the administration of probiotics, which introduce beneficial bacteria to the gut, are explored as potential preventative measures to support a healthy gut microbiome.