In this fifth study examining the relevance of the insulin-like growth factor (IGF) profiles, namely serum IGF-1 levels, its main binding protein, serum IGFBP-3 levels and the IGF ratio (IGFBP-3/IGF-1), we have examined clinical outcomes with respect to the quartile ranges of each parameter measured in 1633 IVF-naïve women. The outcomes were derived from 1035 of these women who initiated 1747 IVF cycles. Of the three parameters, only IGF-1 levels proved relevant to the clinical outcomes. In particular, this study confirmed our earlier report that IGF-1 levels decline across the quartiles with the woman’s advancing age and the proportion of women with IGF-1 levels in the highest quartile comprised the younger, whilst those women ≥40 years were mostly in the lowest quartile (p
