Transferring only one embryo, instead of two, during fertility treatments does not reduce success rates and cuts the likelihood of multiple births, new research shows.
Presented at the European Society of Human Reproduction and Embryology conference on Monday, the Australian research showed the cumulative birth rate was the same regardless of whether one or two embryo had been transferred during the initial treatment.
But there were fewer multiple births, which can be dangerous for both mother and child, when only one embryo was used.
“This is the first time that a study of cumulative pregnancy and live birth rates with five-day-old single embryo transfer has been conducted,” Dr. Jim Catt, the embryology director of Sydney IVF, told the meeting.
“Under the conditions of this study, twin pregnancies can be reduced drastically without compromising a patient’s chance of a successful pregnancy,” he added.
Catt, who studied 382 patients, said women under the age of 38 who had had two embryos transferred in one cycle of treatment had a live birth rate of 50 percent, compared to 36 percent in women who decided to use only one embryo.
But in women who did not succeed the first time and had a frozen embryo transferred during a second attempt, the cumulative birth rate for both groups was 60 percent.
There were three sets of twins among the 107 women who chose to have only one embryo placed in the womb, compared to 90 sets of twins, four of which ended in miscarriage of one or both twins, in the women in the two-embryo group.
The live birth rate per embryo transfer was 36 percent for single embryo transfer and 35 percent for dual embryo.