Clinical outcomes of single versus double blastocyst transfer in fresh and vitrified-warmed cycles.
OBJECTIVE
Assisted reproductive technology has been associated with an increase in multiple pregnancies. The most effective strategy for reducing multiple pregnancies is single embryo transfer. Beginning in October 2015, the National Supporting Program for Infertility in South Korea has limited the number of embryos that can be transferred per in vitro fertilization (IVF) cycle depending on the patient's age. However, little is known regarding the effect of age and number of transferred embryos on the clinical outcomes of Korean patients. Thus, this study was performed to evaluate the effect of the number of transferred blastocysts on clinical outcomes.


METHODS
This study was carried out in the Fertility Center of CHA Gangnam Medical Center from January 2013 to December 2014. The clinical outcomes of 514 women who underwent the transfer of one or two blastocysts on day 5 after IVF and of 721 women who underwent the transfer of one or two vitrified-warmed blastocysts were analyzed retrospectively.


RESULTS
For both fresh and vitrified-warmed cycles, the clinical pregnancy rate and live birth or ongoing pregnancy rate were not significantly different between patients who underwent elective single blastocyst transfer (eSBT) and patients who underwent double blastocyst transfer (DBT), regardless of age. However, the multiple pregnancy rate was significantly lower in the eSBT group than in the DBT group.


CONCLUSIONS
The clinical outcomes of eSBT and DBT were equivalent, but eSBT had a lower risk of multiple pregnancy and is, therefore, the best option.
Fertility Center of CHA Gangnam Medical Center, College of Medicine, CHA University, Seoul, Korea.
Jin Hee
JH
Eum
Fertility Center of CHA Gangnam Medical Center, College of Medicine, CHA University, Seoul, Korea.
Jae Kyun
JK
Park
Fertility Center of CHA Gangnam Medical Center, College of Medicine, CHA University, Seoul, Korea.
So Young
SY
Kim
Fertility Center of CHA Gangnam Medical Center, College of Medicine, CHA University, Seoul, Korea.
Soo Kyung
SK
Paek
Fertility Center of CHA Gangnam Medical Center, College of Medicine, CHA University, Seoul, Korea.
Hyun Ha
HH
Seok
Fertility Center of CHA Gangnam Medical Center, College of Medicine, CHA University, Seoul, Korea.
Eun Mi
EM
Chang
Fertility Center of CHA Gangnam Medical Center, College of Medicine, CHA University, Seoul, Korea.; Department of Biomedical Science, College of Life Science, CHA University, Seoul, Korea.
Dong Ryul
DR
Lee
Fertility Center of CHA Gangnam Medical Center, College of Medicine, CHA University, Seoul, Korea.
Woo Sik
WS
Lee
Blastocyst transfer; In vitro fertilization; Live birth pregnancy rate; Multiple pregnancy; Single embryo transfer
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