Is FMR1 CGG repeat length a predictor of in vitro fertilization stimulation response or outcome

Objective To study a broad range of FMR1 CGG repeat lengths and assisted reproduction technology (ART) outcomes. Design Retrospective cohort study. Setting Private ART practice. Patient(s) Fresh autologous ART stimulation cycles. Intervention(s) None. Main Outcome Measure(s) Oocyte yield, live birth. Result(s) We screened 14,088 fresh autologous ART cycles from 2012 to 2015, of which 4,690 cycles in 3,290 patients met the inclusion criteria. The FMR1 repeat length was statistically significantly but weakly associated with oocyte yield and other markers of ovarian response. The receiver operating characteristic curve analysis suggested extremely limited predictive ability. Moreover, the FMR1 repeat length was not statistically significantly associated with outcomes in multivariable models, including other markers of ovarian reserve. The FMR1 repeat length was not associated with embryo quality or live birth. Only patient age had a strong ability to predict live birth. Conclusion(s) The FMR1 repeat length is associated with ART response, but only weakly. It provides no incremental predictive ability beyond the conventionally used predictors, including patient age, antimullerian hormone concentration, antral follicle count, and follicle-stimulating hormone level. These data suggest a possible role of the FMR1 repeat length within the normal range in ovarian response but demonstrate no clinically relevant indication for testing FMR1 as a predictor of ART outcomes.