Frozen-thawed blastocyst transfer reduces ectopic pregnancy risk: an analysis of single embryo transfer cycles in Japan

Abstract

To evaluate the effect of frozen-thawed blastocyst transfer on ectopic pregnancy (EP) rate. Retrospective analysis. Japanese registry of assisted reproductive medicine. Women who were registered during 2008. None. Rates of live birth, EP, and spontaneous abortion in single blastocyst and cleavage-stage ET cycles in both fresh and frozen-thawed were determined. In the frozen-thawed single blastocyst transfer cycles, 84 EPs of 10,312 clinical pregnancies (0.81%) were reported. There were 25 EPs of 1,361 clinical pregnancies (1.8%) in fresh IVF single blastocyst transfer cycles and 19 of 1,352 (1.4%) in fresh intracytoplasmic sperm injection single blastocyst transfer cycles. The rate of EPs after frozen-thawed single blastocyst transfers varied between 0.56% and 0.97% after stratification by age group. Frozen-thawed blastocyst transfers have reduced EP rates significantly compared with fresh blastocyst transfers.