Randomized study comparing day 2 versus day 3 elective transfer of two good-quality embryos.

The number of embryos transferred is very important to avoid multiple pregnancies without compromising pregnancy rates in fertilization (IVF)/intracytoplasmic sperm injection (ICSI)-embryo transfer (ET). We established criteria for the elective transfer of two embryos (age <40, first treatment cycle, good-quality embryos ≥3) to avoid high-order multiple pregnancies, and reported their usefulness. In the current study, we compared the clinical outcome of day 2 versus day 3 elective transfer of two good-quality embryos, in order to investigate the day of preferential transfer. A total of 228 cycles were treated with IVF/ICSI-ET from August 1999 to August 2002. From this total, 114 patients who were less than 40 years old and also had a first treatment cycle were enrolled in the present study (50.0%). The elective transfer of two good-quality embryos was carried out in 36 cycles (31.6%). Patients were randomized for transfer on either day 2 or day 3 after oocyte retrieval. The pregnancy rate of women who received two good-quality embryos was 44.4% (16 out of 36). The multiple pregnancy rate was 12.5% (two out of 16) and all pregnancies outcomes were twins. There were no significant differences between day 2 and day 3 ET for the following criteria: the number of cycles (24, 12); age (32.8 ± 3.4 years, 32.5 ± 2.7 years); number of oocytes retrieved (10.0 ± 3.3, 9.0 ± 6.0); number of embryos developed (7.6 ± 3.5, 6.9 ± 3.7); and number of good-quality embryos cryopreserved (3.5 ± 2.7, 3.6 ± 2.1). Higher pregnancy and implantation rates were obtained in day 3 ET than day 2 ET (37.5 and 20.8% in day 2 ET 58.3 and 33.3% in day 3 ET); however, there were no significant differences. Day 3 ET appears to be preferable to achieve more viable embryos than day 2 ET. (Reprod Med Biol 2004; : 99-104).