Does chorioamnionitis worsen the outcome of preterm infants? A controversial issue

The term chorioamnionitis is used to describe an intrauterine status of infection/inflammation of either mixed fetal-maternal (choriodecidual space) or fetal origin (chorioamniotic membranes, amniotic fluid, umbilical cord). Histological, microbiological, biochemical and clinical criteria are used to define chorioamnionitis. Histopathological examination of the placenta is the gold standard for evaluating antenatal inflammatory processes that might influence fetal development. Chorioamnionitis is the leading cause of very preterm delivery and its incidence increases with decreasing gestational age. Therefore, it contributes to the high morbidity and mortality of infants born prematurely. In the last decades, several studies have been performed to assess a gestation-independent effect of chorioamnionitis on neonatal and long-term outcome with variable results. The discrepancy observed across studies may be attributable to differences in inclusion and exclusion criteria, disease definitions, methods, and whether potential confounding factors such as gestational age were considered. As underlined by several Authors, the increasingly widespread use of antenatal steroids may have contributed to improve neonatal outcome and can therefore partially explain the different results between studies. In the current review we aim to give an overview and synthesis of a vast amount of existing literature on the association between antenatal infection/inflammation and neonatal and long-term outcome.