ABSTRACT
<p><b>BACKGROUND</b>Embryo quality and receptivity of the endometrium are two factors that determine the results of in vitro fertilization/intra-cytoplasmic sperm injection-embryo transfer (IVF/ICSI-ET). There is no consensus of the optimal transfer strategy for normal responders or high responders. The current study aimed to find the optimal transfer strategy for different subgroups of patients.</p><p><b>METHODS</b>From April 2010 to December 2010, patients who meet the following criteria were included in this study; primary infertility, female age ≤ 35 years, FSH level on female cycle day 2 - 3 ≤ 12 mIU/ml, at least six good quality embryos available on day three. The clinical outcomes using different transfer strategies between normal responders and high responders were reviewed and compared.</p><p><b>RESULTS</b>For the normal responders, the clinical pregnancy rate of day three double-embryo transfer (DET) was comparable to that of day five elective single blastocyst transfer (eSBT), 64.04% vs. 60.33% (P > 0.05). For the high responders, the clinical pregnancy rate of day five eSBT was significantly lower than that of day three DET, 43.35% vs. 57.21% (P < 0.05). For the high responders, the rates of clinical pregnancy and implantation in frozen-thawed embryo transfer (FET) cycles were notably higher than in eSBT cycles (64.56% vs. 43.35% and 62.11% vs. 43.35% respectively) (P < 0.05).</p><p><b>CONCLUSIONS</b>For normal responders, eSBT might be an applicable strategy to reduce multiple pregnancy rates while maintaining acceptable overall pregnancy rates. And in order to reduce multiple pregnancies and increase the chance of pregnancy of high responders, FET may be a preferable strategy.</p>