<qa>  What is the name of the test used to compare abdominal rSO2 patterns?Data are analyzed using IBM SPSS Statistic version 20.0.0 IBM Corporation, IBM Corporation Armonk, New York, United States. Clinical characteristics in the study groups are compared by t-test for continuous variables and chi-square test for categorical variables. Mann-Whitney U test is used to compare abdominal rSO2 patterns in response to the first feed between groups 1 and 2. A multivariate analysis is also performed to assess the effect of possible confounding factors. 