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I started doing IVF in 1985 when the pregnancy rate at the Jones Institute, the most successful program in the country, was 15 percent. This success was achieved while transferring six embryos at a time. As a consequence, we experienced many high order multiple pregnancies that did not always end well. Aside from pregnancy and neonatal complications, many of the marriages also suffered.
Thankfully, today IVF is so much more successful and we can attain pregnancies in greater than 60 percent of retrievals for women under 40. These rates are accomplished while transferring one, two, or at most three embryos at a time. Cryopreservation, or freezing embryos, has also improved our pregnancy rates per retrieval giving us multiple opportunities to get a patient to conceive from a single IVF stimulation and retrieval.
In an effort to encourage safer single embryo transfer and avoid risky multiple pregnancies, we introduced a program in 2007 at East Coast Fertility for patients who transferred one embryo at a time. For these patients we offered free cryopreservation, storage and frozen embryo transfers until a live baby was born.
Still, patients don't commonly choose single embryo transfer. From our experience, similar to others', there was no significant difference in pregnancy rates between patients who chose to transfer one embryo vs. those who chose to transfer two embryos. There was a trend, however, towards higher rates for the two-embryo transfer group that was practically eliminated when frozen embryo transfers were added. These groups were age matched with no difference except for a 40 percent twin rate and one triplet in the two-embryo transfer group compared to the single-embryo transfer group in which no twins were created.
It is hoped that these results will encourage more good prognosis patients to transfer a single embryo, which is the safer option.