Pregnancy outcome after blastocyst stage transfer comparing to early cleavage stage embryo transfer

Abstract

Blastocyst transfer has been introduced as an alternative for improving the chance for in vitro fertilizations (IVF) implantation. The present study was to evaluate pregnancy rates when embryo transfer was performed either on day 2–3 (cleavage stage) or on day 4–5 (blastocyst stage). This randomized clinical trial included 118 infertile women. All the study subjects underwent controlled ovarian stimulation using a long protocol and randomized into two groups. BS group (n = 57), the culture was extended to day 5 (blastocyst stage) and in the CS-group (n = 61), embryo culture was continued to day 3 (cleavage stage). Ongoing pregnancies, abortion, implantation rate were evaluated. No significant differences were seen in the pregnancy rate between the two groups (33.3% in the BS group versus 27.9% in the CS group; p = 0.519). Abortion, implantation rate in two groups are not significant. Despite the lack of statistical difference between the two study groups, our data suggest that blastocyst transfer may be associated with a higher pregnancy and an overall better implantation rates. However, further studies with larger sample size are mandatory to confirm these findings.

Chinese abstract

囊胚移植已经作为一种提高IVF植入机会的选择方法，本研究目的是评估在2-3天（卵裂期）移植或4-5天（囊胚期）移植的妊娠率。这个临床随机试验有118例不孕妇女。所有实验对象都采用长方案进行控制性卵巢刺激并随机分为两组。BS组(n=57)胚胎培养延长至5天（囊胚期），CS组(n=61)胚胎培养持续3天（卵裂期）。评估持续妊娠率、流产率、植入率。两组间妊娠率没有显著性差异(BS组为33.3% ，CS组为27.9%，p=0.519)。两组间流产率和植入率无显著性差异。尽管两组之间没有明显统计学差异，数据提示囊泡期移植可能有更高的妊娠率和整体更好的植入率。但是需要进一步更大样本的研究来证实这些结果。

• Blastocyst stage
• early cleavage stage
• embryo transfer
• in vitro fertilization failure

Declaration of interest

The authors report no declarations of interest.