Is frozen embryo transfer cycle associated with a significantly lower incidence of ectopic pregnancy An analysis of more than 30000 cycles

Capsule:
Frozen-thawed embryo transfer has been associated with a significantly lower risk of ectopic pregnancy (EP) compared with fresh cycles. Ovarian stimulation might be associated with an increased risk of EP.

Authors:
Bo Huang, Ph.D., Dan Hu, M.D., Kun Qian, Ph.D., Jihui Ai, Ph.D., Yufeng Li, Ph.D., Lei Jin, Ph.D., Guijin Zhu, M.D., Hanwang Zhang, Ph.D.

Volume 102, Issue 5, Pages 1345–1349

Abstract:

Objective:
To analyze the incidence of ectopic pregnancy (EP) in fresh compared with frozen-thawed cycles.

Design:
Retrospective cohort study.

Setting:
Teaching hospital in the People’s Republic of China.

Patient(s):
31,925 women undergoing in vitro fertilization–embryo transfer (IVF-ET) from January 2006 to December 2013.

Intervention(s):
Fresh IVF-ET compared with frozen-thawed ET (FET).

Main Outcome Measure(s):
Incidence of EP with fresh IVF-ET compared with frozen-thawed ET cycles, clinical pregnancy rate, and rate of EP per clinical pregnancy.

Result(s):
For the fresh IVF cycles, 19,173 patients underwent oocyte retrieval; 15,042 had an ET, 6,431 of these patients (42.7%) had a clinical pregnancy, and among these 297 (1.97%) appeared to have an EP. The group of patients undergoing frozen-thawed ET (12,752 patients) included 12,255; there were 5,564 pregnancies (45.4%) and 124 ectopic implants (1.01%). The incidence of an EP per clinical pregnancy was 4.62% for the fresh transfer group compared with 2.22% for the frozen-thawed cycle group; this difference was statistically significant. In addition, the fresh ET cycles had the highest risk of EP, followed by day-3 embryo FET cycles; blastocyst FET cycles had the lowest risk of EP, and the differences were all statistically significant.

Conclusion(s):
Frozen-thawed ET cycles were associated with a statistically significantly lower risk of EP when compared with fresh cycles. These findings are consistent with ovarian stimulation being associated with an increased risk of EP.

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