Can a day 7 embryo result in healthy pregnancy?

Transferring embryos on day seven is not very common and is usually only taken into consideration in certain circumstances where the embryos could benefit from longer culture. Here are several instances in which a day 7 embryo transfer could possibly be considered:

1. Delays in development: If the embryologist observes that the embryos are developing at a slower pace than anticipated, extending their time in culture might potentially increase the embryos’ likelihood of maturing into healthy blastocysts.

2. Increased risk of genetic abnormalities: If there is ever any doubt as to the genetic normalcy of the embryos, more time in culture could be necessary to do more testing and identify healthier embryos.

3. Limited number of viable embryos: If there are only a limited number of viable embryos available for transfer, the fertility team might choose to extend the culture to day 7 in the hope of selecting the most viable embryo.

4. Previous failed attempts: In order to increase the likelihood of success, the fertility experts may decide to use a day 7 transfer for a patient who has had many IVF setbacks.

5. Particular patient conditions: Sometimes a day 7 transfer is done in response to specific patient challenges, such as uterine conditions or susceptibility concerns.

Chances of success with day 7 blastocyst

In research conducted on more than 2,500 patients in Oxford, England, it was discovered that 43.1% of viable Day 7 embryos and 67.7% of viable Day 5 blastocysts were euploid.

The researchers observed that day 7 blastocysts had a somewhat decreased implantation rate as compared to the younger embryos.

However, blastocysts with various rates of growth were found to have comparable developmental survival, whether they were vitrified on day 5, day 6, or day 7.

Recent research has challenged this practice of ceasing embryo culture on day 6 as more studies confirm that embryos with blastulation upto day 7 can be viable, euploid and totally result in healthy pregnancies and babies.

For patients who would not have any viable embryos if the culture ended on Day 6, extending the culture to Day 7 may effectively broaden the selection of transferable embryos. This is especially true for women who are older (over 35), since their embryos take slower to blastulate and are thus more vulnerable to cycle cancellation.