Effect of double cleavage stage versus sequential cleavage and blastocyst stage embryo transfer on clinical pregnancy rates

Objective:To compare clinical pregnancy rates following sequential day-3 and day-5 embryo transfer with double or sequential cleavage-stage transfers.Methods:This study enrolled 242 patients undergoing gonadotropin-releasing hormone antagonist protocol and fresh embryo transfer.Basal follicle stimulating hormone,luteinizing hormone,serum estradiol and anti-Müllerian hormone levels and controlled ovarian stimulation outcomes were noted.Of 242 women,135 underwent double embryo transfer on day 2 or day 3(the double group),54 women underwent sequential embryo transfer on day 2 and day 3(the D2/D3 group),and 53 underwent sequential embryo transfer on day 3 and day 5(the D3/D5 group).Clinical pregnancy rates were compared among the groups.Results:Female age,body mass index,basal follicle stimulating hormone,luteinizing hormone and estradiol levels were similar among the groups(P>0.05).The D3/D5 group had a significantly higher number of metaphaseⅡoocytes,fertilized oocytes and good quality embryos on day 3 compared with the double group and the D2/D3 group(P<0.001).Clinical pregnancy rates in the double,D2/D3 and D3/D5 groups were 26.6%(36/135),16.6%(9/54)and 37.7%(20/53),respectively.There was no significant difference in clinical pregnancy rates between the double group and the D2/D3 group(P=0.204)or the D3/D5 group(P=0.188).The D3/D5 group had significantly higher clinical pregnancy rates compared with the D2/D3 group(P=0.025).Conclusions:Sequential cleavage-stage transfer(D2/D3)or cleavage stage and blastocyst transfer(D3/D5)does not improve clinical pregnancy rates compared with double cleavage-stage embryo transfer.Although sequential transfer seems to be an effective option in certain patient populations,routine application of this technique might not be a suitable approach in an unselected population to improve assisted reproductive technology outcomes.