Study	Reason for exclusion
Mercer 2001	Women recruited to the trial did not have corticosteroids before entry The objective of the trial was to evaluate the need for and benefits of weekly antenatal corticosteroids in women at risk of preterm birth. 189 women between 23 and 32 weeks at risk of preterm birth were randomised to weekly antenatal corticosteroids or to a control group where corticosteroids were given if indicated before 35 weeks, if the pregnancy was expected to last more than 1 week The primary outcome was antenatal corticosteroids given within 7 days of preterm birth (< 35 weeks) (optimal exposure). In the control group only one third of infants < 35 weeks’ gestation received optimal antenatal corticosteroid exposure. Weekly corticosteroids doubled optimal exposure although the vast majority gave birth > 34 weeks
Thorp 2000	Women recruited to the trial were not randomised to receive repeat corticosteroids but antenatal phenobarbital. The abstract is a secondary multivariate analysis of this trial assessing if duration of antenatal betamethasone is associated with perinatal outcome