Experts Weigh in on New IVF Embryo Transfer Research
Posted Jan 20 2012 12:00am
New research claiming to have found the ideal number of embryos to transfer during an IVF treatment has re-opened discussion among fertility experts as to what really is considered best practice.
The new research, published by researchers in the UK, says that discretion can be applied which choosing whether to transfer 1 or 2 embryos during an IVF treatments, however 3 embryos should never be considered.
"In both age-groups, transfer of three embryos did not increase the live birth rate over that seen after transfer of two embryos, but was associated with an increased risk of adverse perinatal outcomes,“ wrote the authors Professor Debbie Lawlor from the University of Bristol's School of Social and Community Medicine and Professor Scott Nelson from the University of Glasgow's Centre for Population and Health Sciences.
In their study, Lawlor and Nelson studied 124,128 IVF procedures which resulted in a total of 33, 514 live births and examined the relationships between live births, multiple births, preterm births, and severe preterm births.
They found that women over the age of 40 were more likely to have a live birth with 2 embryo transfer and were less likely to have adverse outcomes. Women under the age of 40, on the other hand, also were more likely to have a live birth with a 2 embryo transfer but were more likely than the older women to have an adverse outcome with 2 embryos as opposed to 1. Neither group benefited from a 3 embryo transfer.
"Our findings provide some support for the transfer of two embryos in women older than 40 years, because the risks of preterm and low birth weight were lower than those in younger women,“ reported the researchers. “In older and younger women, the transfer of two embryos was associated with greatest live birth rates. A clear implication of our study, is that transfer of three embryos should no longer be supported in women of any age."
Dr. Norbert Gleicher, world-renowned reproduction specialist and founder of the Center for Reproduction in New York, remarked that while the study's findings are interesting, there are some limitations.
“While this study investigates a very large number of IVF ( in vitro fertilization ) cycles from the National Registry in the UK, these cycles were all performed under rather strict national guidelines, restricting embryo transfer numbers. The data, therefore, is undoubtedly somewhat biased because British transfer guidelines are much more restrictive than, for example, U.S. Guidelines.”
According to Dr. Gleicher, this study will likely not impact the proposed single embryo transfer legislation in the US, which would prevent doctors from implanting more than one embryo during an IVF procedure.
However, he remarks, it does provide further evidence to the fact that age must be considered when making the decision as to how many embryos to transfer. This, in addition to other factors including as medical contraindication to twinning, patient’s desire in favor or against twins, and embryo quality should all also be taken into consideration by both the doctor and patient prior to embryo transfer in an IVF procedure.