Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:Contrary to our finding, the association of long intervals and pregnancy complications, such as pre-eclampsia, preterm birth and SGA,were also reported in some studies.4,7 Conflicting results may be due to lack of standardized definitions used for IPI.
Category: