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Cleavage stage versus blastocyst stage embryo transfer in assisted conception
D Blake1, M Proctor, N Johnson
1Glycoscience Research Department, Auckland University of Technology, Private Bag 92006, Auckland, New Zealand, 1020. debbie.blake@aut.ac.nz
The Cochrane Database of Systematic Reviews
|June 22, 2002
Summary
Blastocyst culture in in vitro fertilization (IVF) shows no significant difference in live birth rates compared to early embryo transfer. Routine blastocyst culture should be approached cautiously due to increased cancellation rates.
Area of Science:
- Reproductive Medicine
- Embryology
- In Vitro Fertilization (IVF)
Background:
- Extended embryo culture to blastocyst stage (5-6 days) aims to improve IVF success by enhancing uterine-embryo synchrony and self-selection of viable embryos.
- Despite widespread adoption, conclusive evidence supporting blastocyst culture over early cleavage embryo transfer is limited.
- Understanding embryo nutrient requirements has driven the shift towards longer culture periods.
Purpose of the Study:
- To determine if blastocyst stage embryo transfers result in higher success rates than cleavage stage embryo transfers.
- To assess and compare the overall embryo utilization rates between blastocyst and early cleavage stage transfers.
Main Methods:
- Systematic review and meta-analysis of randomized controlled trials (RCTs) comparing early cleavage versus blastocyst stage embryo transfers.
- Searches conducted across multiple databases including Cochrane, MEDLINE, EMBASE, and Bio extracts.
- Data extraction and quality assessment performed independently by two reviewers; meta-analysis used odds ratios and weighted mean differences.
Main Results:
- No significant difference observed in live birth rates or clinical pregnancy rates between blastocyst and early cleavage transfers.
- Implantation rates showed no overall difference, though a subgroup analysis of sequential media trials suggested higher rates for blastocyst transfer.
- Embryo transfer cancellation rates were significantly higher in the blastocyst group, while embryo freezing rates showed no difference in RCTs.
Conclusions:
- Current evidence from RCTs indicates minimal differences in major outcomes between early embryo transfer and blastocyst culture.
- Routine blastocyst culture warrants caution due to increased cancellation and potential decrease in cryopreservation rates.
- Sequential media trials show promise for improved implantation and pregnancy rates, but higher live birth rates require further validation.