The effects of antenatal corticosteroids therapy on very preterm infants after chorioamnionitis

To evaluate the effectiveness of antenatal corticosteroids (AC) therapy on outcomes of very low birthweight infants with histologic chorioamnionitis. We performed a retrospective analysis of 10,935 single infants born at a gestational age between 22 + 0 and 33 + 6 weeks and birth weight < 1,500 g. Clinical data were obtained from the Neonatal Research Network that included the tertiary neonatal intensive care units throughout Japan between 2003 and 2008. Data of 7,896 infants were available for the period 2003-2008 and were included in the analysis. According to logistic regression analysis, AC were significantly associated with reduced mortality [odds ratio (OR) = 0.50; p < 0.001], lower incidence of respiratory distress syndrome (OR = 0.72; p < 0.001), neonatal seizure (OR = 0.65; p = 0.003) and intraventricular hemorrhage (OR = 0.68; p = 0.001) in cases after histologic chorioamnionitis compared with the cases had no AC therapy (n = 3,271 vs. 4,625). Antenatal corticosteroids were significantly associated with reduced mortality [odds ratio (OR) = 0.60; p < 0.001] among the cases without histologic chorioamnionitis. In the retrospective population-based study in Japan, AC exposure was significantly associated with a lower rate of death and neurological morbidity in cases with histologic chorioamnionitis. These outcome data in Japan will be important for further improvement of antenatal practice and care.