In Infertility - Freezing, thawing a single embryo (French version)

Abstract

Introduction: This retrospective analysis has evaluated
the extent to which transfers of frozen single embryos increase
cumulative pregnancy rates.
Material and methods: It included IVF cycles carried out from 2001 to 2005 (n=1758). Patients were assigned to three groups according to the number of embryos frozen: A “no cryopreservation”, B “a single embryo frozen”, C
“several embryos frozen”. Implantation and pregnancy rates
after fresh embryo transfers were analysed as a function of the
number of embryos frozen. Embryo survival and pregnancy
rates after the transfer of a single thawed embryo were compared between groups B* (only one embryo frozen and thawed) and C* (last embryo of the cohort thawed).
Result(s): Pregnancy rate per fresh embryo transfer increased significantly with the number of embryos frozen: 16.2%
in A, 21.4% in B, 26.5% in C (p<0.001). For single thawed embryos, survival was higher in C* (91.7%) than in B* (72.6%; p<0.05). Pregnancy rate was also significantly
higher in C* (19.4% versus 0%).
Conclusion(s): The freezing of single embryos is of no
benefit in cumulative pregnancy rates. Embryo transfer strategies should therefore be reviewed.