Antenatal corticosteroids and placental histology in preterm birth.

To assess the effects of antenatal corticosteroid use on placental histopathology, we have reviewed a database of 463 consecutive non-anomalous singleton liveborns delivered at less than 32 weeks between April 1988 and December 1994, of which 280 received one or more doses of corticosteroids for promotion of fetal lung maturation. Patients were grouped by the number of corticosteroid doses received (analyzed as none, 1, 2 and 3 or more doses). Clinical and demographic factors were recorded prospectively. Placental histopathology was reviewed blinded to clinical factors except gestational age, and 42 distinct placental lesions were examined and scored for severity. Data were analyzed by contingency tables, one-way analysis of variance, and linear regression analysis. Among clinical variables, univariate analysis showed that the number of corticosteroid doses was significantly related to presence of labour prior to delivery, pre-eclampsia, premature rupture of membranes and clinical suspicion or diagnosis of chorioamnionitis. Using linear regression analysis with these clinical variables as confounders, increased number of doses of antenatal corticosteroids was related to increased severity of villous fibrosis and stromal mineralization, and fewer villous infarcts.