A fertilized egg becomes a two-cell embryo.
After the embryo develops for 5 days, it has divided many times, and is now called a "blastocyst". Traditional
IVF transfer of embryos usually takes place 2-3 days after fertilization. Recent advances allow us to successfully
transfer embryos at day 5, but to what benefit and trade-off?
The benefit to a blastocyst transfer is
that implantation rates are higher. This is likely because of two reasons. The transfer timing is more physiological
(at day 2 the embryo is in the fallopian tube) and the embryo is likely healthier than the average day 2 transfer,
since it has already proven to survive 5 days.
Therefore, when we used to transfer 4 embryos
at day 2, we had no idea as to how many of them would make it to day 5, or make it to a live birth. Potentially,
all 4 embryos could survive and the result would be quadruplets. Today, we can see that if all 4 embryos make it
to day 5, we shouldn't transfer all 4 embryos. The risk of multiple births would skyrocket if we did. Similarly,
the risks of multiple births, especially higher order multiple births, should decline if we only transfer one or
two healthy blastocysts.
On the downside, it is possible to have
few or no embryos survive to day 5 to transfer. It is unknown whether those embryos would have survived beyond
the day 2 transfer either. But, if they were transferred at day 2, at least we would have known the outcome.
This is cutting edge technology. The Blastocyst
Transfer is still relatively new. This should be discussed with your physician. |

Typical IVF Treatment Cycle

How much does IVF cost?

About Pregnancy Rates

Blastocyst Transfer

What is ICSI?
|