Blastocyst Transfer on Day 5

If you are having IVF, you may be a candidate to have embryos returned to you on day 5-6 after egg (oocyte) retrieval instead of the customary day 3.

Waiting until day 5-6 will allow us to select those embryos that have developed to the blastocyst stage. A blastocyst is an embryo that has developed two different cell types, one type will become the placenta and the other will become the fetus. Embryos that develop to the blastocyst stage by day 5-6 may have a better chance of implanting. Any blastocysts that are not transferred may be frozen for use at a later time.

Blastocyst transfer reduces the chance of triplets and increases the pregnancy rate.

<< Day 3 embryo with 8 cells  

<< Day 5 embryo (Blastocyst) with distinct inner cell mass (ICM) and Trophectoderm (TE). The ICM develops into the baby and the TE develops into the placenta. 

If no blastocysts have developed by day 5-6, we may recommend against having an embryo transfer. This decision may save you from waiting for 11 days after a day-3 transfer only to have a negative pregnancy test. Currently, about 30-40% of our day-3 transfers result in pregnancy.

Regardless of their rate of development, we can always return the embryos on day 5-6 at your request.

Our recommendation that you wait until day 5-6 for blastocyst transfer will be made 3 days after oocyte retrieval (day 3). The decision will be based on the number of embryos that have grown 8 or more cells that morning. The decision is made as follows:

• Day-3 embryo transfer if fewer than 3 embryos have 8 or more cells on the morning of day 3.
• Because we will not know how the embryos develop until the morning of day 3, you must be prepared to come in on short notice for an embryo transfer.
• Day 5-6 embryo transfer if 3 or more embryos have 8 or more cells on the morning of day 3.

We would like to emphasize the following:

• Returning blastocysts on day 5-6 does not guarantee a pregnancy.
• Blastocyst transfer is a relatively new procedure and only a few IVF babies have been conceived by this method.
• There could be unknown and long-term after-effects.
• Blastocyst embryo transfer may be associated with an increased rate of identical twins.
• We cannot predict if and when multi-cell embryos will become good quality blastocysts. We may or may not know on the morning of day 5 or day 6 that we will have blastocysts for transfer later that day. Therefore, you must be prepared to come in for a blastocyst transfer on short notice.