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

Objective: To evaluate the effect of frozen-thawed blastocyst transfer on ectopic pregnancy (EP) rate.
Design: Retrospective analysis.
Setting: Japanese registry of assisted reproductive medicine.
Patient(s): Women who were registered during 2008.
Intervention(s): None.
Main Outcome Measure(s): Rates of live birth, EP, and spontaneous abortion in single blastocyst and cleavage-stage ET cycles in both fresh and frozen-thawed were determined.
Result(s): 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.
Conclusion(s): Frozen-thawed blastocyst transfers have reduced EP rates significantly compared with fresh blastocyst transfers.
(Copyright © 2011 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.)