[Elective single embryo transfer policy at 48/72 h: which results after fresh transfers and frozen/thawed transfers?]. / Politique de transfert électif d'un embryon à 48/72h: quels résultats après transferts frais et transferts d'embryons congelés ?

OBJECTIVES: To evaluate our elective single embryo transfer policy performed at 48/72h and define predictive factors of pregnancy after frozen/thawed embryo transfer. METHODS: Analysis of 289 elective single embryo transfers (eSET) performed in a selected population in the ART center of Marseille University Hospital from January 2005 to December 2011, as well as the 325 following frozen/thawed embryo transfers performed in this population between May 2005 and December 2012. RESULTS: Cumulative pregnancy rate/oocyte retrieval was of 62.6%; 45% of the couples obtained the birth of at least one child. During this studied period, cumulative pregnancy and delivery rates in the whole population remained stable while multiple delivery rate/delivery clearly decreased. Elective single embryo after frozen/thawed transfer gave satisfying results (24.6% pregnancy/transfer) only in the lack of lysis or in case of mild lysis (1-25%) of the transferred embryo. CONCLUSION: The implementation of an eSET policy gives satisfying results, depending largely on embryo quality. By proposing eSET to a well-targeted population, chosen both on clinical and biological criteria, a clear reduction of cumulative multiple delivery rate/delivery was obtained in our center over this period, without any global decrease of cumulative pregnancy rate/attempt. Embryo quality is a major factor of success, especially in frozen/thawed cycles. The elective single embryo frozen/thawed transfer should be carried out only if embryo lysis after thawing does not exceed 25%.