Frozen thawed embryo transfer is associated with a significantly reduced incidence of ectopic pregnancy

Capsule:
The incidence of pregnancy of unknown location and visualized EP were each significantly reduced in transfers of thawed embryos when compared with fresh embryo transfers.

Authors:
Bruce S. Shapiro, M.D., Ph.D., Said T. Daneshmand, M.D., Laura De Leon, M.D., Forest C. Garner, M.Sc., Martha Aguirre, Ph.D., Cynthia Hudson, M.S.

Volume 98, Issue 6, Pages 1490-1494, December 2012

Abstract:

Objective:
To compare the incidence of ectopic pregnancy after fresh embryo transfer and thawed embryo transfer.

Design:
Retrospective cohort study.

Setting:
Private fertility center.

Patients:
This retrospective study included 2,150 blastocyst transfers, including all 1,460 fresh autologous blastocyst transfers and all 690 transfers of autologous blastocysts derived from post-thaw extended culture (PTEC) of thawed bipronuclear oocytes in the 8-year study period 2004-2011.

Main outcome measures:
Visualized ectopic pregnancy (VEP) and treated persistent pregnancy of unknown location (TPPUL).

Results:
The rate of VEP was 1.5% in pregnancies in fresh autologous cycles, which was significantly greater than the rate of 0.0% with autologous PTEC. The rates of TPPUL were 2.5% and 0.3% in these two groups, respectively, a difference that was also statistically significant (relative risk 7.3, 95% CI 1.7-31.0).

Conclusions:
Relative to fresh transfer, thawed embryo transfer was associated with significantly reduced incidence of ectopic pregnancy. These findings are consistent with ovarian stimulation increasing the risk of ectopic pregnancy.

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