Prediction of in vitro fertilization rates from semen variables.

OBJECTIVE

To assess the value of semen variables for predicting fertilization rates.

DESIGN

Measures of the fresh semen and the motile sperm fraction used for insemination were related to the fertilization rate by multiple regression analysis. The regression model was then used to construct a two-dimensional clinical chart.

SETTING

University-affiliated reproductive medicine unit.

PATIENTS

The results of 294 IVF cycles were analyzed retrospectively. Selection criteria were: [1] first cycle of IVF; [2] tubal and/or male factor infertility; and [3] four or more oocytes inseminated.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

The fertilization rate was related to measured variables of the fresh semen and the motile sperm fraction used for insemination. Fertilization rate was categorized as poor (< 35%) or acceptable (> or = 35%).

RESULTS

Multiple regression analysis demonstrated a strong correlation between the fertilization rate and the combined indexes of percentage normal morphology and grade of motility in the fresh semen and percentage progressive motility in the motile sperm fraction. A two-dimensional chart that expressed these relationships was constructed. Its accuracy of prediction was 77% for poor fertilization and 95% for acceptable fertilization.

CONCLUSIONS

The fertilization rate is strongly correlated with percentage normal sperm morphology in the fresh semen and the percentage progressive motility in the motile sperm fraction used for insemination. The clinical chart provides a simple but powerful tool for predicting fertilization outcome.