In premature infants, the risk of neonatal sepsis is increased mainly due to?

In premature infants, the risk of neonatal sepsis is significantly increased primarily due to their immature immune system. Premature birth interrupts the normal development of the immune system, leaving neonates with reduced levels of essential immunoglobulins, limited ability to mount effective immune responses, and an underdeveloped barrier against infections.

The biological immaturity in preterm infants includes not only fewer white blood cells to fight infections but also a less efficient function of those that are present. This makes them more susceptible to infections such as sepsis, which can occur when bacteria enter the bloodstream. The risk is heightened in the early days after birth when these infants are particularly vulnerable.

Although low birth weight, environmental factors, and genetic predisposition may play roles in overall health and susceptibility to various conditions, it is the immaturity of the immune system that is the most critical factor leading to the increased risk of sepsis in this population.