Limited implantation success of direct-cleaved human zygotes: a time-lapse study

Objective: To evaluate embryos with direct cleavage (<= 5 hours) from two to three cells (DC2-3) and correlate this morphokinetic parameter to implantation and ongoing pregnancy. Design: Clinical multicenter retrospective study. Setting: Private in vitro fertilization (IVF) centers. Patient(s): From three clinics, a total of 979 treatments including 5,225 embryos using autologous or donated oocytes, of which 1,659 embryos were transferred. Intervention(s): None. Main Outcome Measure(s): Clinical pregnancy confirmed by ultrasound in week 7. Result(s): Of the total embryo cohort, 715 (13.7%) underwent direct cleavage from two to three cells, 1,659 embryos were transferred to recipients, and 109 of the transferred embryos cleaved directly from two to three cells (6.6%). Only one DC2-3 embryo was known to result in a clinical pregnancy (1%) and 80 (73.4%) DC2-3 embryos did not implant. Of the 1,550 embryos transferred not showing DC2-3, 203 embryos were from treatments with 100% implantation (13.1%), and 804 (51.8%) embryos did not implant. The known implantation rate of DC2-3 embryos was statistically significantly lower than for embryos with a normal cleavage pattern (1.2% vs. 20.2%, respectively). Conclusion(s): Embryos with DC2-3 had a statistically significantly lower implantation rate than embryos with a normal cleavage pattern, suggesting that rejection of these embryos for transfer could improve the implantation rate. (Fertil Steril (R) 2012;98:1458-63. (C) 2012 by American Society for Reproductive Medicine.)