Intrauterine Inflammation and its Sequelae: Does Chorioamnionitis Really Matter for Outcome of Very Low Birth Weight Infants?

Infections in utero and chorioamnionitis are major risk factors for spontaneous, very early premature birth. Thus chorioamnionitis contributes significantly to prematurity-associated morbidity and mortality. Evidence for a gestation-independent effect of chorioamnionitis on the outcome of very low birth weight infants is much more difficult to obtain as most of the studies addressing this issue lack a normal "control group", as prematurity is mostly associated with some kind of prenatal pathology with a potential influence on neonatal outcome. Moreover, major advances in perinatal and neonatal care for this high-risk group have mitigated the impact of chorioamnionitis on morbidity and mortality of very low birth weight infants. Histological chorioamnionitis is associated with a lower incidence and severity of respiratory distress syndrome. However, short-term maturational effects on the lung are associated with a higher susceptibility for postnatal noxious events, such as mechanical ventilation, thus contributing to the risk of bronchopulmonary dysplasia. Data regarding the importance of chorioamnionitis for brain damage of the very premature infant are inconsistent although meta-analyses have shown an increased risk of cystic periventricular leukomalacia and cerebral palsy after exposure to inflammation in utero. Very recent epidemiological studies suggest a role of chorioamnionitis in the aetiology and pathogenesis of retinopathy of prematurity.