The outcomes of sequential embryo transfer in patients undergoing in vitro fertilization with frozen-thawed embryos: A retrospective study

Aim To explore whether sequential embryo transfer benefits patients with repeated implantation failure (RIF) undergoing frozen-thawed embryo transfer (FET) cycles. Methods We included 311 patients with a history of RIF in this retrospective study. We did sequential transfers with a cleavage embryo on day 3 and a blastocyst on day 5 in 77 patients; blastocyst transfers with two blastocysts on day 5 in 80 patients; and cleavage embryo transfers with two cleavage embryos on day 3 in 154 patients. We compared clinical outcomes between the three groups. Results The clinical pregnancy rate was comparable between the blastocyst transfer group (48.8%), the sequential transfer group(48.1%) and the cleavage embryo transfer group (48.1%). There was no statistically significant difference found (p > 0.05). The ongoing pregnancy and multipregnancy rates were also comparable between the three groups (p > 0.05). The early miscarriage rate was significantly higher in the sequential transfer group (32.4%) compared with the blastocyst group (12.8%) and the cleavage embryo group (12.2%) (p < 0.05). However, after adjusting for confounders, there was no significant difference in early miscarriage rates in the sequential transfer group compared with the blastocyst group (odds ratio [OR], 2.97; 95% confidence interval [CI], 0.85-9.24; p = 0.07) and the cleavage embryo group (OR, 3.03; 95% CI, 0.94-8.06; p = 0.08). Conclusions Sequential embryo transfer failed to improve clinical outcomes for patients with RIF.