Trends in 'poor responder' research: lessons learned from RCTs in assisted conception

BACKGROUND A substantial minority of women undergoing IVF will under-respond to controlled ovarian hyperstimulation. These women—so-called ‘poor responders’—suffer persistently reduced success rates after IVF. Currently, no single intervention is unanimously accepted as beneficial in overcoming poor ovarian response (POR). This has been supported by the available research on POR, which consists mainly of randomized controlled trials (RCTs ) with an inherent high-risk of bias. The aim of this review was to critically appraise the available experimental trials on POR and provide guidance towards more useful—less wasteful—future research. METHODS A comprehensive review was undertaken of RCTs on ‘poor responders’ published in the last 15 years. Data on various methodological traits as well as important clinical characteristics were extracted from the included studies and summarized, with a view to identifying deficiencies from which lessons can be learned. Based on this analysis, recommendations were provided for further research in this field of assisted conception. RESULTS We selected and analysed 75 RCTs. A valid, ‘low-risk’ randomization method was reported in three out of four RCTs. An improving trend in reporting concealment of patient allocation was also evident over the 15-year period. In contrast, <1 in 10 RCTs ‘blinded’ patients and