Thawed embryo transfer and ectopic pregnancy: a meta-analysis

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; I 2 = 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; I 2 = 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; I 2 = 45%). Conclusion Our results indicate that in contrast to fresh embryo transfers, thawed D3 or D5 embryo transfers can reduce the rate of EP.