Comparison of the results of an assisted-reproduction program related with the day of follicular aspiration

The proper time for the oocyte retrieval allow us to obtain good quality oocytes In assisted reproduction techniques, improving fertilization and pregnancy rates. The follicular aspiration has been done by vaginal ultrasounds when we can see at least 3 follicles > or = 16 mm diameter. To compare oocyte quality, fertilization and pregnancy rate-according to the day of the follicular aspiration. 438 cycles were studied in the Instituto para el Estudio de la Concepción Humana in Monterrey Mexico, comparing oocyte quality, fertilization and pregnancy rate. If egg retrieval was done on day 12 of the cycle, we obtained a mean of 7.61 good quality oocytes, 51% of them fertilized and the pregnancy rate was 36.8%, when the aspiration was performed on day 13 of the cycle, we obtained a mean of 7 good quality oocytes, 59% of them fertilized and the pregnancy rate was 34%, and if the oocyte retrieval was on day 14 of the cycle, we obtained a mean of 6.42 good quality oocytes, 57% of the fertilized and the pregnancy rate was 31.7%. The oocyte quality, fertilization and pregnancy rate were slightly better if the oocyte retrieval was performed on day 12 or 13 of the cycle, rather than day 14. However this was no statistical significative.