The embryologist had good news for Jenny and Erin every day. The embryo continued to grow strongly, dividing rapidly until, just before the transfer it reached seven cells in size.
Seven cells is huge for a three-day embryo. We were surprised Jenny and Erin's embryo had grown so large. All of our past embryos but one had only reached the four cell size. The only one which had grown larger was only five cells at day three.
Large embryos are much more likely to create a successful pregnancy. With four-celled embryos we only had a one in six chance of having a baby. Yet both of our children resulted from four-cell embryos and pregnancy occurred on our first try during both of our embryo transfer cycles.
Things were looking good for Jenny and Erin, but there was a problem...