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Updated: Apr 15, 2026
Modified MicroSecure Vitrification: A Safe, Simple and Highly Effective Cryopreservation Procedure for Human Blastocysts
Published on: March 2, 2017
Single vitrified blastocyst transfer maximizes liveborn children per embryo while minimizing preterm birth
Kate Devine1, Matthew T Connell2, Kevin S Richter3
1Program in Reproductive and Adult Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Rockville, Maryland; Shady Grove Fertility Reproductive Science Center, Washington, District of Columbia; Shady Grove Fertility Reproductive Science Center, Rockville, Maryland.
Single frozen blastocyst transfer (FBT) significantly reduces the risk of multiple and preterm births while maintaining high live-birth rates. Transferring thawed blastocysts one at a time can lead to more liveborn children per couple.
Area of Science:
- Reproductive Medicine
- Embryology
- Obstetrics
Background:
- Assisted reproductive technology (ART) involves transferring embryos to achieve pregnancy.
- Frozen blastocyst transfer (FBT) is a common ART procedure.
- The decision between single or double FBT impacts live-birth rates and risks of multiple gestations.
Purpose of the Study:
- To compare live-birth rates, blastocyst-to-live-birth efficiency, gestational age, and birth weights between single and double thawed blastocyst transfers.
- To evaluate the safety and efficacy of single versus double FBT in a large patient cohort.
Main Methods:
- Retrospective cohort study analyzing 1,696 autologous frozen blastocyst transfers (FBT) from January 2009 to April 2012.
- Included were transfers of one or two vitrified-warmed blastocysts with good morphology (grade BB or better).
- Compared outcomes included live birth, blastocyst-to-live-birth efficiency, preterm birth, and low birth weight.
Main Results:
- Double FBT resulted in a higher live birth rate per transfer but significantly increased the incidence of twin births (33% vs. 0.6%).
- Double FBT was associated with statistically significant increases in preterm birth and low birth weight, even in singletons.
- Single FBT demonstrated a higher liveborn child rate per transferred blastocyst (38% vs. 34%) and significantly reduced risks of multiple and preterm births.
Conclusions:
- Single FBT offers excellent live-birth rates while substantially decreasing the risks of multiple and preterm births.
- Patients undergoing FBT should be informed that transferring thawed blastocysts one at a time can lead to a greater overall number of liveborn children per couple.
- Single FBT is a safer and potentially more efficient strategy for maximizing live births while minimizing adverse pregnancy outcomes.
