Single Embryo Transfer Recommended in Most IVF Procedures

By Rachel Walden |

The process of in vitro fertilization — in which embryos are created outside a woman’s body and then implanted in her uterus — has become increasingly common in the United States. In 2010, 61,564 infants were born using an a form of assisted reproduction technology (ART), and almost all of those resulted from IVF.

A common IVF practice has involved transferring multiple embryos to a woman’s body in one cycle. This was thought to increase the likelihood that at least one embryo would successfully result in a live birth. The average number of embryos transferred at one time is two to three.

While this strategy makes sense theoretically, it is not risk free. Transferring more than one embryo creates a risk for multiple pregnancies, such as twins or triplets, which makes the pregnancy higher risk and increases the risk of premature birth and low birth weight. (Single pregnancies created via IVF are also thought to be at a higher risk for prematurity, low birth weight, and congenital anomalies, though researchers aren’t certain whether this is due to the IVF techniques or the underlying infertility problem.)

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Recently, researchers have been studying whether single embryo transfer might be a better option. Some have suggested that birth rates might be similar when single embryos are transferred.

The research has been convincing. In a joint practice committee statement, the Society for Assisted Reproductive Technology and the American Society for Reproductive Medicine concludes that with improving technology, single embryo transfer (SET) is an increasingly better choice for achieving pregnancy while avoiding multiples.

The statement notes that SET may be particularly appropriate for women with the best chance of a good outcome, such as those who are under 35 or on their first or second treatment cycle, and that women ages 35 to 40 could also elect SET if they have “top quality” embryos of the proper stage available for transfer.

The authors also note that the United States has “lagged behind” the rest of the world in focusing on SET. For example, the National Institute for Health and Care Excellence (NICE) in the UK recommends single embryo transfer for most women and no more than two at a time for anyone.

For more on single-embryo transfers, read this excerpt from “Our Bodies, Ourselves.”

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  1. Marco says:

    The clinic I go to bevliees that if an embryo can not make it to day 5 then it is abnormal. I had always had doubts in this and thought maybe the Dr.’s were full of BS. Then i did my last cycle with donor eggs. We had 13 awesome embryo’s on day 3. All 7 plus cells grade 1 and 2, 1 being the highest. We did genetic testing on all the embryo’s and 7 out of the 13 were abnormal. 5 of the genetically abnormal ones stopped growing between day 3 and 4. I did end up with 2 genetically abnormal ones that made it to blast stage. Looking at these results i see where the Dr’s could be correct that if an embryo is good it will last till day 5. A lot also plays into the competency of the lab. Some labs have a harder time cultivating the embryo’s to day 5 so they transfer on day 3. Day 3 vs Day 5 transfers go along with so many other uncertainties of IVF. There is no secret code or magic solution to get a BFP.