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Live birth after fresh embryo transfer vs elective embryo cryopreservation/frozen embryo transfer in women with polycystic ovary syndrome undergoing IVF (FreFro-PCOS): study protocol for a multicenter, prospective, randomized controlled clinical trial

Yuhua Shi1, Daimin Wei1, Xiaoyan Liang2, Yun Sun3, Jiayin Liu4, Yunxia Cao5, Bo Zhang6, Richard S Legro7, Heping Zhang8 and Zi-Jiang Chen1*

Author Affiliations

1 Center for Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong University, Reproductive Medical Hospital affiliated to Shandong University, No. 157 Jing Liu Street, Shizhong district, Jinan 250001, China

2 Reproductive Medical Center of the Sixth Affiliated Hospital, Sun Yat-Sen University, No. 17 Sogoulin Road, Tianhe district, Guangzhou 510655, China

3 Reproductive Medical Center of RenJi Hospital, Shanghai Jiaotong University School of Medicine, No. 1630 Dong Fang Road, Shanghai 200127, China

4 Reproductive Medical Center of Jiangsu Province Hospital, No.300 Guangzhou Road, Nanjing 210029, China

5 Reproductive Medical Center of the first Affiliated Hospital, Anhui Medical University, No. 218 Ji Xi Road, Hefei 230022, China

6 Reproductive Medical Center, Guangxi Maternal and Child Health Hospital, No. 225 Xin Yang Road, Nanning 530003, China

7 Department of Obstetrics and Gynecology, Penn State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA

8 Department of Biostatistics, Yale University School of Public Health, 60 College Street, New Haven, CT 06510, USA

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Trials 2014, 15:154  doi:10.1186/1745-6215-15-154

Published: 2 May 2014



Polycystic ovary syndrome (PCOS) patients are at increased risk of pregnancy complications, which may impair pregnancy outcome. Transfer of fresh embryos after superovulation may lead to abnormal implantation and placentation and further increase risk for pregnancy loss and complications. Some preliminary data suggest that elective embryo cryopreservation followed by frozen–thawed embryo transfer into a hormonally primed endometrium could result in a higher clinical pregnancy rate than that achieved by fresh embryo transfer.


This study is a multicenter, prospective, randomized controlled clinical trial (1:1 treatment ratio of fresh vs. elective frozen embryo transfers).. A total of 1,180 infertile PCOS patients undergoing the first cycle of in vitro fertilization (IVF) or intracytoplasmic sperm injection will be enrolled and randomized into two parallel groups. Participants in group A will undergo fresh embryo transfer on day 3 after oocyte retrieval, and participants in group B will undergo elective embryo cryopreservation after oocyte retrieval and frozen–thawed embryo transfer in programmed cycles. The primary outcome is the live birth rate. Our study is powered at 80 to detect an absolute difference of 10 at the significance level of 0.01 based on a two-sided test.


We hypothesize that elective embryo cryopreservation and frozen–thawed embryo transfer will reduce the incidence of pregnancy complications and increase the live birth rate in PCOS patients who need IVF to achieve pregnancy.

Trial registration Identifier: NCT01841528

Frozen–thawed embryo transfer; In vitro fertilization; Live birth; Polycystic ovarian syndrome