Are factors that influence oocyte fertilization also predictive? An assessment of 148 cycles of in vitro fertilization without gonadotropin stimulation.

Fertilization characteristics of 152 consecutively obtained oocytes in an in vitro fertilization (IVF) program employing only natural and clomiphene citrate-induced cycles were retrospectively analyzed. Fertilization occurred significantly more often (1) in women with tubal infertility, (2) in spontaneous cycles, and (3) in cases of secondary infertility. Grade I sperm motility from the original semen sample and the duration of infertility were also significant influencing factors. A similar sperm correlate was not identified on samples after sperm migration. Preovulatory follicular fluid steroids, progesterone (P), estradiol (E2), E2:P ratio, and luteinizing hormone (LH), as well as baseline plasma LH and the magnitude of the LH surge did not correlate with fertilization. However, when the identified factors were used to predict fertilization (discriminant analysis), only 58.3% of oocytes were correctly classified. This data supports the concept of performing IVF as a test in its own right.