Study selection and data collection
We included published or unpublished randomized controlled trials (RCT) or quasi-RCT that included women at risk of preterm birth (before 37 weeks), and comparing any corticosteroids against each other or against placebo regardless the dose or schedule.
The primary outcomes for the mother (however defined by study authors) were chorioamnionitis and endometritis/puerperal sepsis, for the foetus/neonate were neonatal death and RDS and for the child neurodevelopmental disability at two years follow-up (blindness, deafness, moderate/severe cerebral palsy, or development delay/intellectual impairment16.
The secondary outcomes were: maternal death; perinatal death; foetal death; chronic lung disease; intraventricular haemorrhage; mean birthweight; and low birth weight.
Three authors (KK, DC, AC) independently screened titles and abstracts and reviewed the full-texts of the potentially eligible studies by using EROS17 and COVIDENCE18 software, and independently extracted data into a pre-piloted data extraction form including the RoB of using the Cochrane tool6.  We classified a summary RoB for each study as high risk if at least one domain is classified as high risk and the others as low/moderate risk.