Revisiting the progesterone to oocyte ratio.

OBJECTIVE: To critically evaluate the P to oocyte (O) ratio (P/O) in the prediction of live birth in assisted reproductive technology (ART) cycles.
DESIGN: Retrospective cohort study.
SETTING: Not applicable. PATIENT(S): A total of 7,608 fresh autologous ART ET cycles. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Live birth. RESULT(S): Generalized estimating equation (GEE) models and receiver operating characteristic curves assessed the ability of P, O, and the P/O ratio to predict live birth. In univariate GEE models, P, O, and P/O were each associated with live birth. However, in multivariate GEE models, the P/O ratio was not associated with live birth, but P alone was. This suggested that converting P and O into a ratio of P/O was not more helpful than the two independent variables themselves. Measures of overall model fit further suggested that P/O did not increase the predictive ability of the model over P and O alone. Receiver operating characteristic curves using incremental predictors further demonstrated that the P/O provided no incremental improvement in predicting live birth over P and O separately. CONCLUSION(S): These data suggest that P and O have utility in prediction modeling but demonstrate that additional oocytes were not protective from the negative association of P with live birth. There was no incremental improvement related to the P/O ratio specifically for predicting live birth over each variable independently. Published by Elsevier Inc.