Elective single-embryo transfer in frozen blastocyst transfer cycles

Abstract

OBJECTIVE: The number of embryos transferred has been shown to be the most important factor for IVF-associated multiple pregnancies. Although several reports have suggested the value of single fresh embryo transfer in good prognostic patients, very few data is available with regard to the feasibility of single frozen embryo transfer. In this study, we evaluated single-embryo transfer in our frozen blastocyst program. DESIGN: Retrospective study performed in an academic assisted reproduction program. MATERIALS AND METHODS: Day 5 and day 6 blastocysts graded as 3BB or better were frozen and thawed between January 2004 and December 2007. A frozen-thawed blastocyst with good blastomere survival (>80%) and blastocoele re-expansion was defined as a good-quality embryo. A single good quality frozen-thawed blastocyst was transferred in 39 patients who had good prognosis of pregnancy establishment following the fresh IVF. To compare the outcome between single- and double-embryo transfers, double-embryo transfers were divided into 2 groups, those with only 1 good quality blastocyst and those with 2 good-quality blastocysts. Double-embryo transfers without good-quality embryos were excluded from this study. The rates of pregnancy and implantation were compared among groups. RESULTS: As shown in Table1, no difference exists in patient age at blastocyst freezing among groups. A similar rate of clinical pregnancy was obtained for selective single-embryo transfer when compared to double-embryo transfer containing only 1 good embryo (30.8% vs 34.8%). No twins were observed in the selective single-embryo transfer group. Although there was a significant trend towards higher clinical pregnancy rate in double-embryo transfers with 2 good-quality blastocysts, 28.8% of the pregnancies were twins.Table 1Selective single transferDouble transfers with 1 good-quality embryoDouble transfers with 2 good-quality embryosP ValueNo. of transfers3966140Age at freezing (mean ± SD)33.8 ± 3.634.5 ± 3.834.2 ± 3.80. 8422No. of positive HCG [n (%)]14 (35.9)∗28 (35.1)75 (53.7)∗0.0886, ∗,∗ 0.0509No. of clinical pregnancy [n (%)]12 (30.8)23 (34.8)59 (42.1)0.3427No. of implantation [n (%)]12 (30.8) ∗25 (18.9)∗76 (27.1)0.0952, ∗,∗ 0.034No. of twins [n (%)]02 (8.7)17 (28.8)0.0004 Open table in a new tab CONCLUSIONS: Single-embryo transfer in selected patients with a good-quality frozen-thawed blastocyst yields acceptable clinical pregnancy rate without multiple pregnancies.