Slightly lower incidence of ectopic pregnancies in frozen embryo transfer cycles versus fresh in vitro fertilization-embryo transfer cycles: a retrospective cohort study.

Objective: To analyze the incidence of ectopic pregnancies (EPs) in fresh and frozen/thawed cycles.

Design: A retrospective cohort study on the incidence of EPs in all fresh IVF cycles from January 2002 until December 2012. This was compared with the incidence of tubal pregnancies in patients undergoing transfer of frozen/thawed embryos during the same time period.

Setting: The IVF program at Fertility Center, AZ Jan Palfijn, Gent, Belgium.

Patient(s): A total of 11,831 patients undergoing IVF (i.e., the entire population of the IVF Center) were retrospectively analyzed.

Intervention(s): The IVF cycles, fresh IVF-ET, frozen/thawed ET. Laparoscopy for treatment of EP.

Main Outcome Measure(s): Primary end point: incidence of EPs in both groups. Secondary end points: clinical pregnancy rate (PR), rate of EPs per clinical pregnancy.

Result(s): In the fresh IVF cycle group, 10,046 patients underwent oocyte retrieval; 9,174 of them had an ET; 2,243 of these patients had a clinical pregnancy. Of these, 43 (0.47%) appeared to have an ectopic localization of their pregnancy. In the group of the patients undergoing frozen/thawed ET (1,785 patients) there were 467 pregnancies and 6 ectopic implants (0.34%). The incidence of the EPs per established clinical pregnancy was 1.92% for the fresh vs. 1.28% for the frozen/thawed cycles.

Conclusion(s): No significant difference could be demonstrated on the incidence of EP in fresh IVF cycles vs. frozen/thawed cycles in a large cohort of patients.