Day 2

On Day 1 (Thursday) all we learn is the number of eggs that fertilized successfully. That number turned out to be big: 14.  On Day 2 (Friday) we get more information: by then, the embryos have developed enough that they start to diverge in quality.  So when the embryologist calls on Day 2, she reports not only how many embryos continue to develop, but a grade for each one. 

For Days 2 and 3, the grading scale is a simple 1-5 overall grade where 1 is outstanding, 3 is average, and 5 is not likely to survive.  On Day 2, they're looking for embryos to be 4 cells.  The grade is based in part on whether there has been adequate division (ie, whether there are in fact 4 cells) and then in part on the subjective quality of the cells. The principle "quality" concern is with fragmentation: each time a cell divides, little pieces of cell break off and get loose.  The less of this fragmentation you see in an embryo, the better it is. So each day the embryologist gets the embryos out of the incubator and puts them literally under a microscope, which she uses to give them a good once-over and assign each one a grade.

So, this is the way we graded out on Friday:

3 4-cell embryos at Grade 1
4 4-cell embryos at Grade 2
1 3-cell embryo at Grade 2
5 2-cell embryos at Grade 2
1 2-cell embryo at Grade 3

Recall that Grade 1 is Outstanding quality, Grade 2 is Good, and Grade 3 is Average.  So as of Friday, we had 13 embryos of good-to-outstanding quality and 1 of average quality.

As a result, it was decided yesterday that we'll wait for a Day 5 transfer.  This will allow the embryos time to differentiate themselves; that is, there will be more time for the differences between the best of them to become noticeable.  As we understand it, this means each individual embryo transferred will have a better chance of implanting and growing into a baby.