Numerical dose-compensated in vitro fertilization inseminations yield high fertilization and pregnancy rates

Objective: To evaluate in cases with morphologically abnormal sperm whether fertilization and pregnancy rates are increased by normalizing the number of sperm inseminated and whether biomarkers can identify cases of reduced or failed fertilization. Design: Prospective studies of sperm morphology and function. Setting: University hospital assisted human reproduction program. Patient(s): Partners of 308 women undergoing IVF. Intervention(s): Motile sperm populations were assessed for sperm head morphology, for surface receptors for mannose and progesterone binding, and the ability to undergo a free mannose-induced acrosome reaction. Zinc in seminal plasma was determined by atomic absorption spectroscopy. Main Outcome Measure(s): Sperm morphology was associated with fertilization and clinical pregnancy rates. Biomarker analyses were correlated with fertilization rates using Kruskal-Wallis tests, chi(2) tests, and Spearman rank order correlations. Result(s): Fertilization and pregnancy rates after numerical dose compensation inseminations were indistinguishable between men with differing percentages of normal sperm. Biomarker deficits were identified irrespective of sperm head morphology in 96% of cases of reduced or failed fertilization. Conclusion(s): Fertilization and pregnancy rates in cases of abnormal morphology are optimized by inseminating at least 25,000 sperm/mL with normal acrosomes. Reduced or failed fertilization can be predicted by testing for molecular deficits in mannose receptor expression and mannose-stimulated acrosome loss. (Fertil Steril(R) 1999;71:1019-28. (C) 1999 by American Society for Reproductive Medicine.).