a1 Service de Gynécologie Obstétrique, Hôpital Bichat Claude Bernard, 46 rue Henri Huchard, 75018 Paris, France.
a2 Department of Obstetrics, Gynaecology and Reproductive Medicine, IVF unit, Bichat Claude Bernard University Hospital, AP-HP, 75018 Paris, France.
a3 INSERM U1018 – CESP, 94807 Villejuif, France.
a4 Department of Reproductive Biology, Eylau – La Muette IVF Clinic, 75116 Paris, France.
The aim of this study was to evaluate the advantages of the two-step embryo transfer (ET) strategy combining a day 2/3 ET with a day 5/6 blastocyst transfer. In an observational comparative study, 400 infertile women were enrolled from two assisted reproductive technology (ART) units according to inclusion criteria: age below 42 years and at least three embryos obtained on day 2 thus allowing an extended in vitro culture. Two groups were defined according to the ET strategy adopted: group 1 had a two-step ET; and group 2 had a day 2/3 ET with (subgroup 2a) or without (subgroup 2b) blastocysts cryopreserved on day 5/6. Live birth rate was significantly higher in group 1 than in subgroups 2a and 2b (36.5% versus 29.4% and 13.4%, respectively; p < 10−3). Multiple pregnancy rates were comparable between groups. After adjusting on major prognostic factors, the two-step ET strategy was still associated with a significantly higher live birth rate than the day 2/3 ET (OR = 2.23; 95% CI: 1.32–3.77). The two-step ET provides better live birth rates than the cleavage-stage ET. It does not increase multiple pregnancy rates if the number of embryos transferred is limited. It also prevents cycle loss when embryos fail to develop into blastocysts.
(Received November 01 2010)
(Accepted May 14 2011)
(Online publication October 06 2011)
c1 All correspondence to: Chadi Yazbeck. Service de Gynécologie Obstétrique, Hôpital Bichat Claude Bernard, 46 rue Henri Huchard, 75018 Paris, France. Tel: +33 1 40 25 77 20. Fax: +33 1 40 25 76 00. e-mail: firstname.lastname@example.org