Frozen-thawed blastocyst transfer in natural cycle: feasibility in everyday clinical practice.

PURPOSE: Transfer of frozen-thawed embryos in natural cycle is gaining consensus but evidence on this approach is scanty. The aim of this study is reporting on the feasibility of this type of policy in everyday clinical practice.

METHODS: We retrospectively selected all women undergoing the procedure between July 2013 and December 2014. During the study period, women were systematically scheduled for natural cycle if they referred regular menstrual cycles. Hormone replacement therapy (HRT) was conversely prescribed if the woman had irregular menstrual cycles or if the monitoring of the natural cycle failed. The analysis exclusively focussed on the first cycle per woman.

RESULTS: Overall, 251 women were selected. HRT was initially chosen in 52 women, leaving 199 women suitable for the natural cycle. This procedure could be performed in 194 of these women (97%, 95% CI 95-99%). Two additional women initially allocated to HRT ultimately performed the blastocyst transfer with natural cycle. Overall, 196 were thus treated with natural cycle (78%, 95% CI 73-83%). The basal characteristics of the women who did and did not undergo natural cycles were similar with the exceptions of serum FSH (p < 0.001) and AMH (p = 0.03). The live birth rate did not also differ (34% versus 31%, p = 0.63). Characteristics of women treated with the natural cycle who did (n = 67) and did not (n = 129) achieve a live birth did not differ.

CONCLUSION: Frozen-thawed blastocyst transfer in natural cycle can be successfully performed in the vast majority of women.