Statistical analysis
The collected data was coded and entered to the Statistical Package for Social Science (IBM- SPSS v.25, SPSS Inc) for analysis. The variables listed were analysed and compared between the groups. The quantitative data were presented as mean and standard deviation when their distribution is parametric and as median and range when their distribution is nonparametric. Qualitative variables were presented as number, percentages, or proportions. The confidence interval was set to 95% and the margin of error accepted was set to 5%. P-value was considered significant if P ≤ 0.05. Appropriate statistical tests were used to compare the variables. The confidence interval was set to 95% and P-value considered significant if P ≤ 0.05. Subgroup analysis was done for gestation >28 weeks and between surfactant types (Curosurf, Survanta, Neosurf)