Single embryo transfer is an option in frozen embryo transfer.
BACKGROUND
A good strategy to decrease multiple pregnancy rate in assisted reproduction technology (ART) is the use of single embryo transfer (SET).


METHODS
This retrospective study analysed 1647 frozen embryo transfers carried out during 1998-2003 in Helsinki University Central Hospital; of these, 872 were double embryo transfers (DETs) and 775 SETs. The SET group included 140 (18.1%) elective SETs (eSETs).


RESULTS
The yearly rate of SETs in frozen cycles increased from 28 to 66%. Overall, the clinical pregnancy rate per frozen embryo transfer was 30.7% and the delivery rate 22.6%. The delivery rate was significantly higher in DET cryocycles than in SET cryocycles (25.7 versus 19.2%, respectively; P < 0.01). In DET cryocycles, the multiple delivery rate was 21.9%, 10 times higher than that observed in cryocycles with SET (2.0%) (P < 0.0001). When eSET was applied, no difference in delivery rate was observed when compared with cryocycles with DET (28.6 and 25.7%, respectively).


CONCLUSIONS
SET can be used in frozen cycles to reduce multiple delivery rates.
Department of Obstetrics and Gynaecology, Helsinki University Central Hospital, Finland. christel.hyden-granskog@hus.fi
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Hydén-Granskog
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Unkila-Kallio
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Halttunen
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Tiitinen
D015925:Cryopreservation / Q000379:methods; D010064:Embryo Implantation; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D009865:Oocytes / Q000166:cytology; D011247:Pregnancy; D011256:Pregnancy Outcome; D018873:Pregnancy Rate; D011272:Pregnancy, Multiple; D012189:Retrospective Studies; D013997:Time Factors