Early-cleavage versus blastocyst stage embryo transfer: a prospective comparative study

Area of Science:

• Reproductive Medicine
• Embryology
• Infertility Treatment

Background:

• Embryo transfer (ET) timing is a critical factor in assisted reproductive technologies.
• Optimizing ET day may enhance clinical pregnancy and live birth rates in IVF-ICSI cycles.

Purpose of the Study:

• To investigate the impact of embryo transfer day on clinical pregnancy rates (CPR) and live birth rates (LBR) in IVF-ICSI.
• To compare outcomes between day 2, day 3, and day 5 (blastocyst) embryo transfers.

Main Methods:

• Retrospective analysis of 757 patients undergoing IVF-ICSI between 2012 and 2017.
• Patients stratified into three groups based on ET day: Day 2 (n=43), Day 3 (n=633), and Day 5 (blastocyst, n=81).
• Comparison of basal parameters and IVF-ICSI outcomes including CPR and LBR.

Main Results:

• Day 2 transfer group showed significantly lower CPR (19.5%) and LBR (14.6%) compared to Day 3 (CPR 36.9%, LBR 30.4%) and Day 5 (CPR 39.0%, LBR 35.1%).
• Patients undergoing Day 2 transfers were older with poorer ovarian response and less favorable endometrial thickness.
• Grade 1 embryos were more prevalent in groups with positive clinical pregnancy and live birth.

Conclusions:

• Earlier embryo transfer (Day 2) negatively impacts clinical pregnancy rates in IVF-ICSI.
• Older infertile women, often poorer responders, should not delay fertility treatments due to potential negative effects of early ET.