Breathing easier

As I sat on hold with my health insurance rep while waiting to board the plane, an incoming call came. I knew that area code meant there was no letting this one go to voicemail. I hurriedly asked to put him on a brief hold, turning the tables on my insurance company, to get the news. The "good news" was quickly passed along—two euploids, a low-level mosaic, and a high-level mosaic. And so, yet again, I found myself in a space for which I hadn't mentally prepared. I was waiting for the euploid/aneuploid break-down. I knew mosaics were unusual. And now we had two??

Two more euploid embryos! And some... mosaics? It's time for another dive into the medical literature.

I dove in and quickly surfaced with one fun fact: mosaicism happens during early cell divisions as the embryo is developing. In other words, this issue stems from neither my eggs nor Nicolas's sperm. So, one point for these aging eggs—I'm now 6 embryos deep into pre-implantation genetic testing and haven't yet come across a faulty egg among the day 6 survivor cohort. It's nice to feel like I'm not entirely broken and withered out and generally past my prime. But feelings won't help me understand what's left in the freezer, which is just where you'll find my low-level mosaic—Spring informed me that she can be considered as a back-up. A what now?

Our testing facility labels embryos as low-level mosaics if 20-40% of the biopsied cells were found to be abnormal. In other words, this girl's trophectoderm (the bit that would become the placenta) is 60-80% okay. When a small sample of cells taken from that far away from the future baby's body are for the most part normal, odds are that a baby born from this embryo would be chromosomally normal too. 

Mosaics are categorized by a few things:

• What fraction of cells were affected?
• How many chromosomes were impacted?
• Is it a whole chromosome issue or just a segment of one?
• What cell type is affected—inner cell mass (future body), trophectoderm (future placenta), or both?

In our low-level mosaic's case, we've got the best possible answer to the first of these three: just 20-40% of cells were affected, only one chromosome is at play (chromosome 5), and only a segment of that chromosome was duplicated. As per the final question, only the trophectoderm got biopsied, so we can't answer that. To the extent that we can evaluate this embryo, it's as good as they come in the world of mosaics. Per the medical literature, "[low-level mosaic] embryos have equivalent developmental potential as fully euploid ones." Put that way, it kind of sounds like we just got 3 good embryos.

A recap on our standing after cycle 3: we've got ourselves 4 (or 5) embryos graded as shown here.

So what's next? We already had to pull the trigger if we hoped to squeeze in one last cycle before this summer's Eurotrip. That trigger got pulled. My next—and now, final—surgery is scheduled for mid-to-late July. As it stands, we have a 93% chance of a live birth without even counting our low-level mosaic. It's time to call a wrap on these medical hurdles and cringe-worthy bills.

I don't want to count our chickens before they're hatched, but it's fair to say we can start breathing easier.