2012년 미국불임학회 (ASRM) P-381 The late cleaved embryos, frozen cycle is better than fresh cycle. (늦게 분열하는 수정란인 경우 동결배아 이식 주기가 보다 좋은 임신율을 보인다.)

J. H. Lee, Y. Y. Kim, I. H. Park, H. G. Sun, S. G. Kim, K. H. Lee.
Infertility Lab., mamapapa & Baby Obstetrics and Gynecology Clinic, ULSAN, Republic of Korea

OBJECTIVE

In general, the late cleaved-embryos have low implantation potential in fresh embryo transfer cycles, may be due to embryo-endometrium asynchrony. However, FETs seems to improve embryo-endometirium synchrony by control of thawing day. The aim of this studyis to compare the implantation potential of the late cleaved-embryos (≤6 cell) on day 3 in frozen thawed embryo transfers and Fresh embryo transfers.

DESIGN

Retrospective study.

MATERIALS AND METHODS

We analyzed 468 cycles of the late cleaved embryos from January 2010 to January 2012. The patient was divided by two groups : group A (n=271), Fresh late cleaved embryo trnasfer cycels, group B (n=197), Frozen-thawed late cleaved embryo transfer cycles. Cryopreserved embryos were transferred to patients either in natural cycle or in a hormonally manipulated artificial cycle. Embryos were frozen on day 3 using a vitrification protocol. Late cleaved embryos were thawed on 1 day before ET and we selected 8-cell embryos developed well on the next day. FETs were performed by same physician on day 3. We compared clinical pregnancy rate between two groups.

RESULTS

There were no differences in patient age (A vs. B, 36.7±4.0 vs.35±4.1), the mean number of transferred embryos (2.1±1.2 vs. 2.2±1.3) and endometrial thickness (10.2±1.6 vs. 10.1±2.0) and embryo quality between two groups. However, the clinical pregnancy rates were significantly higher in group B (34.3%) than group A (26.9%, P.01).

CONCLUSION

In our study, the pregnancy rates of the late cleaved embryos were significantly higher in frozen cycles than fresh cycles. In our results, low implantation potential of the late cleaved embryos can be overcome by thawing 1 day before ET, in FETs. It seems thatthe thawing 1 day before ET of late cleaved embryos enabled more appropriate synchronization between embryonic and endometrial development. Therefore the late cleaved-embryo cryopreservation may be an effective alternative to fresh embryo transfer.