Optimum oocyte retrieved and transfer strategy in young women with normal ovarian reserve undergoing a long treatment protocol: a retrospective cohort study

This study aimed to investigate the relationship between the number of oocytes retrieved and clinical outcomes in young women with normal ovarian reserve who were undergoing their first in vitro fertilization and embryo transfer (IVF-ET) cycle. The transfer strategy based on yielded oocytes was also discussed in this article. A total of 1567 patients who underwent first long protocol of IVF treatment in our reproductive medical center between January 2010 and June 2014 were categorized into five groups based on the retrieved oocyte number, namely, 4 similar to 6, 7 similar to 9, 10 similar to 12, 13 similar to 15, and a parts per thousand yen16. Baseline parameters were similar among the groups. Primary outcome was defined as the cumulative live birth rate (CLBR), and secondary outcomes included the rate of patients with high risks for ovarian hyperstimulation syndrome (OHSS). It was found that the CLBR increased with the number of oocytes, as well as the rate for high risks of OHSS. In fresh cycles, 10 similar to 12 oocyte group demonstrated the highest implantation rate (53.32 %), clinical pregnancy rate (CPR) (73.13 %), and live birth rate (LBR) (61.14 %), with no significant differences. Moreover, both cumulative CPR (CCPR) and CLBR became significantly higher in the 10 similar to 12 oocyte group, compared with 4 similar to 6 and 7 similar to 9 groups. However, when the retrieved oocytes increased to 13 similar to 15 or a parts per thousand yen16, the cumulative results did not have a significant increase. Also, the high risk rate of OHSS was much lower in the 10 similar to 12 group (11.53 %) than that in the 13 similar to 15 group (29.97 %) and a parts per thousand yen16 group (77.30 %). Unconditional multivariate logistic regression analysis showed that when a parts per thousand yen10 oocytes were retrieved, the CLBR increased significantly (P < 0.01). When oocyte number exceeded 16, the CPR of frozen embryo transfer cycle was much higher than that of fresh cycle (P < 0.05). For young women with normal ovarian reserve, retrieving 10 similar to 12 oocytes might result in optimized pregnancy outcomes in a fresh cycle with low OHSS risk and would not compromise cumulative outcomes. When a parts per thousand yen16 oocytes were retrieved, a freeze-all embryo strategy might be preferable.