The immune consequences of preterm birth

Abstract

Preterm birth occurs in 11% of live births globally and accounts for 35% of all newborn deaths. Preterm newborns have immature immune systems, with reduced innate and adaptive immunity; their immune systems may be further compromised by various factors associated with preterm birth. The immune systems of preterm infants have a smaller pool of monocytes and neutrophils, impaired ability of these cells to kill pathogens, and lower production of cytokines which limits T cell activation and reduces the ability to fight bacteria and detect viruses in cells, compared to term infants. Intrauterine inflammation is a major contributor to preterm birth, and causes premature immune activation and cytokine production. This can induce immune tolerance leading to reduced newborn immune function. Intrauterine inflammation is associated with an increased risk of early-onset sepsis and likely has long-term adverse immune consequences. Requisite medical interventions further impact on immune development and function. Antenatal corticosteroid treatment to prevent newborn respiratory disease is routine but may be immunosuppressive, and has been associated with febrile responses, reductions in lymphocyte proliferation and cytokine production, and increased risk of infection. Invasive medical procedures result in an increased risk of late-onset sepsis. Respiratory support can cause chronic inflammatory lung disease associated with increased risk of long-term morbidity. Colonization of the infant by microorganisms at birth is a significant contributor to the establishment of the microbiome. Caesarean section affects infant colonization, potentially contributing to lifelong immune function and well-being. Several factors associated with preterm birth alter immune function. A better understanding of perinatal modification of the preterm immune system will allow for the refinement of care to minimize lifelong adverse immune consequences.

13-Valent Pneumococcal Conjugate Vaccine (PCV13) in Preterm Versus Term Infants

“…15 Previous studies in preterm infants have shown a reduced response to other conjugate vaccines, including those targeting H influenzae type b 16 and Neisseria meningitidis serogroup C. 17 These data, together with the increased risk of IPD in preterm infants, 2,18 highlight the need to ensure that preterm infants are immunized and respond adequately to vaccination against S pneumoniae.…”

Health Care-Associated Infections Among Critically Ill Children in the US, 2007–2012

“…When compared with normal birth weight infants, VLBW infants were .2 times more likely to have CLABSI and nearly 3.5 times more likely to develop VAP. This may be due to decreased innate and adaptive immunity of VLBW infants 28 and higher rates of device utilization, the combination of which increases the risk of HAIs substantially. Despite these challenges, VLBW infants have been the subject of large-scale quality improvement efforts to reduce CLABSI over the past decade, and this likely contributes to the substantial reductions seen.…”

Can neonates born at 34 weeks be classified as late preterm?

“…Soluble proteins and peptides have the ability to opsonize pathogens and, in that way, directly kill them through their antimicrobial properties, thus limiting production of soluble factors, such as immunoglobulins (Ig). Low IgG levels result in a lack of opsonization, leading to deficiencies in phagocytosis [10]. Preterm infants have a reduced pool of neutrophils and monocytes, and their precursors (phagocytic cells), due to the diminished granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) levels [9].…”