Purpose: To examine whether thawed embryo transfers can reduce the rate of EP.
Methods: The PubMed, EMBASE, Cochrane Library databases and two randomized controlled trials registration centers were thoroughly searched until March 2017. The clinical outcomes of IVF/ICSI cycles were compared between thawed and fresh embryo transfer.
Results: Twenty-one articles were included in this meta-analysis. There were 801,464 pregnancies totally (thawed-ET: n = 158,967, fresh-ET: n = 642,497). The ectopic pregnancy rate was significantly lower in the group of thawed-ET than that in the group of fresh-ET (OR 0.69, 95% CI 0.57-0.82; I2 = 83%). We subdivided the data into subgroups for D3 embryo transfer and D5 embryo transfer. We also found that the ectopic pregnancy rate was significantly lower with thawed-ET on D3 than that with fresh-ET (OR 0.67, 95% CI 0.53-0.85; I2 = 0%). The risk of ectopic pregnancy was significantly decreased with thawed-ET on D5 than that with fresh-ET (OR 0.57, 95% CI 0.50-0.64; I2 = 45%).
Conclusion: Our results indicate that in contrast to fresh embryo transfers, thawed D3 or D5 embryo transfers can reduce the rate of EP.
Keywords: Ectopic pregnancy; Fresh embryo transfer; Thawed embryo transfer.