The role of human milk in combating neonatal sepsis and strengthening infant immunity

Neonatal sepsis is a life-threatening condition caused by bacterial, viral, or fungal infections that invade a newborn’s bloodstream within the first 28 days of life. Neonatal sepsis is by far the leading cause of mortality and morbidity not only in preterm but also term babies across the world. Neonatal sepsis is an even bigger problem in developing countries, especially in India where we have a dangerous combination of having a huge population of preterm babies and gram-negative bacterial infections which can be lethal. Overall neonatal sepsis is the single largest contributor to the Neonatal Mortality Rate (NMR). Even in preterm babies, despite advances in respiratory and general care, sepsis remains the major cause of mortality in the NICU.  Neonatal Sepsis if not diagnosed and treated promptly will progress rapidly, leading to systemic inflammation, multi-organ failure, and death. Even with aggressive medical interventions such as early antibiotics and supportive care, mortality is very high and babies who survive often face long-term complications like delays in development, chronic lung infections, and impaired neurodevelopment. Hence the cornerstone of success in overcoming this burden of sepsis lies in prevention and adopting non-invasive practices in the NICU. 

Premature infants, that is infants born <37 weeks of gestation and newborns with low birth weight (<2500 g), are at the highest risk of sepsis due to underdeveloped immune systems contributing to the decreased ability to fight infections, making them more susceptible to infections. Neonatal sepsis can be early-onset, which appears within 72 hours after delivery, is more prevalent in term and near-term babies, and has a significant mortality rate. If not detected and treated early. Several factors contribute to neonatal sepsis such as infections in the mother, extended labor especially over 18 hours, use of instruments for delivery, hospital-acquired infection, and poor hygiene during delivery or postnatal care. On the other hand, late-onset sepsis which happens 72 hrs after birth is more common in preterm babies <34 weeks gestation who are admitted to NICU, these infections may be related to invasive lines, ventilation, or cross infection from other babies in the unit and are by large hospital-acquired infections because of low immunity in these babies. Late-onset sepsis is the single largest contributor to mortality in these premature or low birth weight babies.

Along with hygienic practices providing early nutrition with human milk is one of the most potent defenses against neonatal sepsis. Numerous clinical studies have shown that breast milk on its own as a single factor decreases sepsis and offers protection for these very small babies. Along with the essential nutrients provided by human milk that are necessary for growth and development, it offers several bioactive compounds that play a crucial role in boosting immunity. The bioactive compounds include antibodies such as immunoglobulin A (IgA), immune cells, human milk oligosaccharides (HMOs), anti-oxidants, lactoferrin, and probiotics, which play a vital role in reducing neonatal infection. Clinical evidence shows that early feeding with human milk is associated with a reduced incidence of sepsis. Mother’s milk is the best and when this is not available pasteurised human donor milk (PHDM), from a milk bank, is the next best recommended option. Many clinical trials have demonstrated that PHDM offers protection against neonatal sepsis and should be preferred over formula milk when mother’s milk is not available.

Mechanisms of Protection offered by Human Milk include:

1. Antibacterial Properties: The immunoglobulins such as IgA and secretory IgA coat the intestinal mucosa and prevent the entry of bacteria. Lactoferrin and lysozymes, directly inhibit the growth of harmful pathogens that cause sepsis.
2. Prebiotic Effects: The HMOs in breast milk serve as prebiotics, promoting the growth of beneficial gut bacteria that protect the infant’s gut from harmful pathogens. It also prevents the bacteria from attaching to the intestinal surface. 
3. Enhancement of Immune Response: Breast milk has cytokines and growth factors that stimulate the development of the newborn’s immune system, making it more capable of fighting off infections.
4. Barrier Function: Human milk enhances the gut barrier by preventing the translocation of bacteria from the intestines to the bloodstream which is a common pathway for sepsis.

Overall, Neonatal sepsis is a critical global health issue, with high incidence rates. However, human milk offers a powerful defense, significantly reducing the risk of infections and improving survival outcomes, particularly for preterm and low-birth-weight infants. Expanding access to human milk, through breastfeeding promotion and increasing access to PDHM throughout India, is essential to combating neonatal sepsis and improving neonatal survival. Unfortunately, there still exists a gap in the need to access PDHM in India with only very few functional milk banks.  By leveraging the protective properties of human milk, and continuing with hygienic precautions we can make strides in reducing the burden of neonatal sepsis and safeguarding the health of newborns