The impact of woman's age and sperm parameters on fertilization rates in IVF cycles

Objective: To examine the predictive value of different sperm parameters and the age of a couple on fertilization rate. Material and methods: One-hundred six consecutive sperm samples were analysed before insemination of oocytes in IVF cycles. Sperm count and motility were examined with the Makler Counter Chamber. Morphology was evaluated by the eosin nigrosin and giemsa stains. Membrane integrity was evaluated by the hypoosmotic swelling test (HOST). Results: Using a step-wise logistic regression test the following parameters were all significantly correlated with the fertilization rates: sperm concentration after a 3-h layering (χ ² = 15.85, P < 0.001), sperm motility index (χ ² = 6.12, P < 0.0134), woman's age (χ ² = 6.25, P < 0.012), and the hypoosmotic test (χ ² = 6.63, P < 0.01). A fertilization capacity formula was established by using these four parameters to predict the fertilization capacity of a couple. Significantly lower fertilization rates were detected in elderly women with the partner sperm concentration of 7 x 10 ⁶ /ml after 3-h layering, < 30% swollen spermatozoa in the HOST and motility index score of < 50. Conclusions: By the aforementioned formula, sperm fertilization capacity can be predicted by using simple sperm parameters and women's age. Elderly women with partners who have suboptimal sperm parameters reflected by low fertilization capacity scores may benefit from micro-manipulation procedures.