Pregnancies following the interval double-transfer technique in an in vitro fertilization-embryo transfer program.

In 16 women undergoing IVF-ET, with more than four embryos available, two transfers were performed (24 hr apart), instead of one. The pregnancy rate was 25%, as compared with a pregnancy rate of 6.2% in 16 women having fewer than four embryos available and in whom one conventional transfer was performed. Since in our IVF-ET program, we do not freeze the extra embryos available, the purpose of the double transfer was to use all the embryos available and to improve the chances of finding the "implantation window" open. It is our feeling that multiple transfers may be beneficial to improve the pregnancy rate in an IVF-ET program without freezing facilities. However, a larger controlled clinical trial is necessary, in order to establish the advantages of multiple transfers in terms of pregnancy rate in comparison with the potential disadvantages.