Is bigger better: The association between follicle size and livebirth rate following IVF?

Purpose: To analyze the correlation between lead follicle size at hCG trigger and IVF outcome. Methods: A review of all patients undergoing their first IVF cycle between 1/2005-12/2009 was performed. Four groups were evaluated (<18 mm, 18 - 18.9mm, 19 - 19.9 mm and ≥20 mm), based on the mean diameter of the two largest follicles on day of ovulation trigger (OT); cycle parameters and outcomes were analyzed. Results: 1577 cycles were reviewed. There were no significant differences noted for cycle parameters or outcomes for the 4 groups. However, although LBR was not significantly different, there was a decline noted as lead follicle size increased. Conclusions: Delaying the administration of OT to enhance follicular growth does not appear to improve IVF outcome. Larger lead follicles do not yield a higher percentage of mature oocytes, embryos available for transfer or LBR. A misguided zest to achieve a higher quantity of fertilizable oocytes may impair oocyte and embryo quality.