RESUMO
OBJECTIVE: Determining if fertilization rates can be used as a predictive factor for pregnancy induction in ETIVF-ICSI programs. TYPE OF STUDY: Retrospective, observational and descriptive. MATERIALS AND METHODS: Six hundred and seventy nine cycles of the in vitro fertilization program, using long protocol hypophyseal suppression, stop, or antagonsits, were included. Ovarian stimulation was carried out with menotropines or recombinant FSH. Those patients whose cycle was stopped due to the lack of follicular development were excluded. Variables under study were: age, fertilization percentage, pregnancy rate, pre-ovulatory estradiol levels, number and quality of captured oocytes, transferred embrios and endometrial thickness on the day of transference and the presence of pregnancy. The Pearson P Test with a 95% confidence interval and the Student T Test used to establish differences with a 95% confidence interval statistical analyses were applied. RESULTS: Six hundred and seventy nine cycles were studied, 487 of which used the conventional fertilization method, and 192 used the ICSI method. Mean age among patients was 34 +/- 1.1 years old, with pre-ovulatory estradiol levels of 4,023 +/- 1,134 pg/mL, the average quantity of captured oocytes was 11.7 +/- 3.2 with a capture rate of 69.6%. Mean fertilization rates averaged 54% with a 20.7% pregnancy rates using the transference method. After analyzing the fertilization rate in each group, a statistically significant linear correlation was observed (P = 0.547, CI 95%) with the pregnancy rate. After assigning patients to two different groups: conventional IVF and ICSI, a higher positive correlation was observed (P = 0.827, CI 99%) in the first group. No significant differences were observed in the remaining parameters between both groups, excepting oocyte maturity, where greater prophase I and metaphase II percentages were observed in the ICSI group. When 50% fertilization was taken as the cutting point, a 78.19% negative predictive value was determined, with a 25% positive predictive value, 77.5% sensitivity, and 25.6% specificity. CONCLUSIONS: A fertilization percentage greater than 50% can be used as a pregnancy predicting factor in in vitro fertilization programs.