Two instead of three embryo transfer in in-vitro fertilization.

The rational of transferring two instead of three embryos was studied through 468 in-vitro fertilization (IVF) treatment cycles in 287 couples. The quality of 1224 embryos was determined according to the fragmentation rate and the morphology as good (A) and poor (B). The influence of the number of embryos transferred (two or three) on the pregnancy rate when the same quality or combinations of good and poor quality embryos transferred was examined. When only good quality embryos were transferred the pregnancy rates in double (AA) and triple (AAA) embryo transfer were 40.5 (17/42) and 42.9% (30/70) respectively (not significant). When only poor quality embryos were transferred, the pregnancy rates in double (BB) and triple (BBB) embryo transfers were 11.0% (11/100) and 22.9% (16/70) respectively (P < 0.001). On the other hand, when good and poor quality embryos were transferred together as AB in double and as AAB and ABB in triple embryo transfer, the pregnancy rates were 36.8 (14/38) and 39.9% (59/148) respectively (not significant). There was no difference in the miscarriage rate between double and triple embryo transfers; 16.7 and 18.1% respectively. The multiple pregnancy rate was 14.3% for double embryo transfers and 32.4% for triple embryo transfers (P < 0.001). This study demonstrates that if there is at least one good quality embryo available for transfer, then double instead of triple embryo transfer will not yield a significantly lower pregnancy rate. The influence of the number of embryos transferred on the pregnancy rate became significant when only poor quality embryos were transferred.(ABSTRACT TRUNCATED AT 250 WORDS)