Antenatal corticosteroid timing: accuracy after the introduction of a rescue course protocol

The opportunity for a second course of antenatal corticosteroid did not improve the number of women who delivered within any optimal antenatal corticosteroid window. Administration timing was similar for the initial course and the rescue course, with approximately one-quarter of women delivering within the optimal antenatal corticosteroid window. These findings likely reflect the few circumstances in which rescue antenatal corticosteroid is useful and the poor predictability of preterm birth. Future focus should be aimed at tools to predict the timing of preterm birth to optimize antenatal corticosteroid administration.