Day 3 Embryo Transfer vs. Day 5 Blastocyst Transfer for IVF
Page author Richard Sherbahn MD
2 blastocyst embryos that were transferred with a pregnancy resulting
Transferring 2 blastocysts can yield high pregnancy rates and (almost) no risk for triplets
Unresolved issues regarding blastocyst transfer:
- How do we select the most appropriate candidates for blastocyst transfer?
- How many blastocysts should we transfer?
- At what female age should we consider transferring 3 blasts instead of the usual 1 or 2?
- Would transferring only 1 blast yield too low a pregnancy rate?
- Which couples are most appropriate for transferring only one high quality blastocyst?
- How many couples would have no blastocysts at all for transfer if we cultured all patients embryos until day 5?
Ten years ago, GIFT (egg and sperm transfer to the tubes) and ZIFT (one-day-old embryo transfer to the tubes) were popular because IVF laboratories were not able to attain high pregnancy rates with longer periods of in vitro culture.
Today, most programs have abandoned these much more expensive and invasive tubal procedures and are routinely doing day 3 uterine transfers with much improved pregnancy rates.
Now that we have learned more about human embryonic needs and have improved the IVF culture systems, we are moving toward more routine use of blastocyst transfer. This allows our patients the highest possible pregnancy rates while reducing their risk for multiple pregnancy.
Our IVF program and some others are currently doing blastocyst transfers in selected cases. Very few programs are doing all of their IVF cases with day 5 transfers.
In almost all centers (including ours) that do blastocyst transfer, there are selection criteria for deciding which cases should be transferred on day 5 vs. day 3 transfer. Usually, the criteria are related to one or more of the following factors:
The number of follicles on the day of HCG
The number of fertilized eggs
The number of good quality embryos on day 3
This means that only "good" cases are allowed to have blastocyst transfer at most centers. Because of this "selection bias" for the better cases, pregnancy rates would be expected to be higher with blastocyst transfers as compared to day 3 transfers.
We need to be careful about how we interpret this. For example, a program might have a 30% pregnancy rate for day 3 transfers and a 65% pregnancy rate for day 5 transfers. Patients (and the news media in the US) might then think that couples undergoing IVF should have blastocyst transfer so they will have a much better chance for pregnancy.
However, in reality, if the program did all of their cases as day 5 transfers, the pregnancy rate would be somewhere in between the previous day 3 and day 5 rates - and most likely the overall pregnancy rate for the program would be about the same.
This is not to imply that blastocyst transfer is not a good thing. It is an excellent technique for selecting the embryos with the most viability potential (baby-making potential) and for reducing the risk for triplet pregnancy (if we limit the number transferred to 2). However, it is not a magic bullet that will give a dramatic improvement in pregnancy success rates for all couples having IVF.
Cost for blastocyst transfer
We do not charge extra for blastocyst transfer. See our current fees for IVF.