Journal of Reproduction & Contraception                                         http://www.RandC.cn

2008 Jun; 19(2):93-100                                                        randc@sippr.stc.sh.cn

Factors Influencing Pregnancy Outcome Following Slow Cooling Cryoembryo Transfer and Risk of Multiple Conception

Su-ying LIU, Jin-lan HAN, Bin TENG, Zhu-di LU, Yu ZHENG, Ying CAO, Xiang CAO,

Ning-yi WANG, Bin HUANG, Jing-ming YAN

Shanghai Jiai Genetics & IVF Institute, Obstetrics & Gynecology Hospital, Fudan University, Shanghai 200011,

China

Objective To investigate the factors that influence the potential for cryoembryo implantation

and multiple pregnancy.

Methods In this retrospective study, a total of 937 thawing cycles (859 couples) in which 3286 d 3-embryos were thawed. Rates of implantation, clinical pregnancy and multiple conception following FET were observed.

Results There were significant differences in female age (P<0.05) and number of good quality embryos (P<0.05) between cycles that resulted in pregnancy and those did not. There was a trend toward decreasing rates of implantation, clinical pregnancy and multiple pregnancy with increasing female age. Compared with transferring 1 good quality embryo, clinical pregnancy rate of transferring 2 and 3 good quality embryos increased significantly (P<0.001), there was no significant difference in clinical pregnancy rate between transferring 2 and 3 good quality embryos. Multiple

pregnancy rate increased significantly in the group of transferring 3 good quality embryos (P<0.05),but there was no significant differences in multiple pregnancy rate between transferring 1 and 2 good quality embryos.Younger women (≤ 30 years) also had a significantly higher multiple pregnancy rates (28.13%) than the older ones(>35 years) (13.64%).With an increase in age from ≤ 30 years to>40 years, clinical pregnancy rate declined from 45.61% to 25.00%.

Conclusion Female age and the number of good quality embryos transferred are important factors influencing the clinical and multiple pregnancy rate, reducing the number of good quality embryos transferred may decrease the rate of multiple pregnancy but do not affect the clinical pregnancy rate.

Key words: in vitro fertilization; cryopreservation; embryo transfer; clinical pregnancy; multiple pregnancy