#52 : Cumulative Live Birth Rates (CLBR) According to the Number of Oocytes Retrieved in Minimal Stimulation In Vitro Fertilization (IVF) Treatment

Background and Aims: Ovarian stimulation is necessary for IVF in order to stimulate the development of multiple follicles in a single cycle. To optimize ovarian stimulation, there is a need to know the optimum number of oocytes retrieved to achieve a live birth.

This retrospective study aimed to evaluate the relationship between the number of oocytes retrieved and the cumulative live birth rates among patients undergoing mild stimulation IVF treatment in a private fertility clinic in the Philippines.

Method: Ovulation was induced using clomiphene citrate in combination with lower doses of gonadotropins. Final oocyte maturation was triggered with hCG or GnRHa. Mature eggs were fertilized using intracytoplasmic sperm injection. Only 1 to 2 embryos were transferred per cycle.

Results: A total of 1,431 patients that had 1,817 fresh and frozen transfer cycles were included. Average age of women was 35.70 ± 3.97 (min. 20, max. 46). Binary logistic regression shows that age is a predictor of live birth, with a critical value of 34.6 years.

CLBR was estimated using Kaplan-Meier survival analysis, with the number of oocytes as the time factor. The estimated mean number of oocytes retrieved for cases that had live birth was 8.90 ± 0.30. Half of the cases that had live birth had an estimated oocyte number of 7.0 ± 0.194. Live birth steadily increased with the number of oocytes but declined beyond 25 oocytes. Retrieval of 6 to 9 oocytes was enough to achieve 40-60% CLBR. In comparison, conventional IVF recommends 8 to 15 oocytes to achieve similar CLBR.

Conclusion: Retrieval of lower numbers of oocytes with minimal stimulation IVF can produce desirable success rates comparable to rates achieved with higher numbers of retrieved oocytes in conventional IVF.