Blastocyst Transfer Update-2006

By David R. Meldrum, M. D., Gregory F. Rosen, M. D. and Bill Yee, M. D.

Reproductive Partners Medical Group, Inc.

Beverly Hills, Long Beach and Redondo Beach, California

Typically, embryos from in vitro fertilization are transferred back into a woman's uterus at the 4- to 8-cell stage two to three days after egg retrieval. It has been customary to transfer more than 1 of these early developing embryos in order to maximize the chance of pregnancy. Unfortunately, this practice also increases the risk of multiple pregnancies, i.e. twins, triplets or more.

On average, close to one-half of 4- to 8-cell embryos at day 2 or 3 are chromosomally abnormal.   By culturing these embryos for an additional 2 to 3 days, more chromosomally normal embryos will be selected out naturally and develop to the blastocyst (5-day-old) stage in the laboratory.   Usually, only the best embryos have the ability to grow to the blastocyst stage and the pregnancy rate per blastocyst transferred is better than 3-day-old embryos. This allows the number of embryos transferred to be reduced. This is especially important in women who are 35 years old or older because in this group of women, it has been common practice to transfer 3 or more day 3 embryos. This practice is associated with an increased risk for triplets. Data indicate that if these women receive only two blastocysts, they are as likely, or even more likely to achieve a pregnancy, compared to those who have three or more less-developed embryos transferred. Even in women under age 35, transferring two blastocysts at day 5 may lead to a higher chance of pregnancy than transfer of two embryos at day 3.

There is an increased risk of identical twins with blastocyst transfers.   When this occurs, there is the possibility of triplets, where both blastocysts implant and one of those blastocysts splits. Identical twins have an increased chance of obstetrical complications compared to non-identical twins.

Another advantage of developing all embryos to the blastocyst stage is that it makes embryo cryopreservation (freezing) more efficient, since embryos without the capacity for full development are not frozen.

Blastocyst transfer also allows the option of single embryo transfer. This is particularly helpful to reduce the chance of twins when twins would be more risky, such as with a misshapen uterus due to DES exposure or with certain uterine abnormalities. Any couple wishing to avoid the chance of twins for any reason may choose single blastocyst transfer.  

In natural conception, fertilized eggs do not enter the uterus until five days after fertilization. Some reports suggest that blastocyst transfer may be helpful for some women with multiple failed cycles, since the uterus may be more receptive five days after retrieval and because the uterus is contracting less frequently, therefore being less likely to expel the blastocysts.       

Not all women are candidates for blastocyst transfers.   We typically only recommend this procedure in cycles where there are five or more fertilized eggs.   With fewer embryos, there is a greater chance none of the embryos will develop normally to the blastocyst stage.

Blastocyst transfers can maximize the chance of success with IVF, while limiting the risk of triplets.

RPMG Establishes All-New Bulletin Board: The RPMG Forum

Please visit the all-new version of the Reproductive Partners Medical Group Bulletin Board, the RPMG Forum. Since its inception in 1999, the mission of this bulletin board has been to educate consumers on fertility-related issues. To date we have posted over 60,000 questions and answers and have helped thousands of couples throughout the world better understand their fertility treatment.

To reach the RPMG Forum, go to www.2reproduce.com and go to Bulletin Board in the top navigation. Even if you had been a participant in the previous version, you will need to sign in again with your user name and password. If you have not visited our board before, please read the frequently asked questions and then start posting or just read other's posts. We hope you find this an educational and enjoyable experience.

There are many new search and security features on the new RPMG Forum to help enhance your experience. One example of the capabilities of this state-of-the-art Forum is our ability to establish a special temporary Forum in conjunction with this newsletter's article on "Blastocyst Update-2006" featuring your questions about and comments on blastocyst transfer.