In addition, the study is limited by lack of collection of data on the underlying fertility-related co-morbidities due to exclusion of known contributory co-morbidities at the point of recruitment.<h4>Wider implications of the findings</h4>This study challenges the purported relationship between CD138+ CE and the pathophysiology of CE-associated RPL. This evidence concerns the gene SDC1 and cholesteryl ester measurement.