Types of studies  
Only randomized controlled trials (RCTs) that have compared the four different NRS treatments (HFNC, CPAP, BiPAP and NIPPV) were included. Studies published as peer reviewed abstract form as well as non-english language studies were included in the final synthesis. Neonates with gestational age < 37 weeks with a primary diagnosis of RDS and who were started on a NIV support within the first 24 hours of life. Neonates who had received surfactant via standard practice (INSURE or LISA) prior to randomisation were included.