There is so much information online, pros and cons for both transferring one or two embryos. For every article that states transferring more than one is dangerous, there's another article that says the opposite. For example, here's an Article educating against multiple embryos vs. Why transferring two is the way to go. The thing is that the article educating against multiples is talking about first transfer success rates. Not sixth transfer. They're not taking into consideration someone who has tried single transfers multiple times without results.
In short, the pros to transfer one are a lowered chance of complications or NICU stay and having multiple chances at a transfer in case one time doesn't work (i.e., lining wasn't right). Pros of transferring two is that they "help each other out," there's a higher chance of pregnancy, and if they both stick, two kids for the price of one. I'm not sure these reasons are scientifically proven one way or another. To me it seems to be the opinion of people who have seen success one way or another.
There are multiple considerations when deciding how many to transfer, such as maternal age, embryo quality and size, and PGD/PGS testing. For us, the embryos are all top grade PGD-tested. Maternal age is currently 33, and the embryos are all strong blasts that are even younger.
For all intents and purposes, we are prime candidates to transfer one high-quality, normally-tested 6-day blast. But we did that. Five times. Success rates statistically indicate a live birth for every 3 or 4 transfers of a high-quality blast. But here we are, five times failed and still no pregnancy, let alone live birth.
We have two healthy blasts remaining in the freezer. The doctor said his part about recommending just one at a time but won't oppose if we decide to transfer both. I don't know what the right answer is. On one hand I don't want to risk the pregnancy in any way. The goal is to have healthy babies. A pregnancy complication at 24 weeks with sudden delivery and a prolonged NICU stay is not a success story. I also don't want to transfer two, get a negative beta, and feel like we're back at square one with nothing to show for all these years of trying.
On the other hand, we tried transferring one and it didn't work. How many times can we do the same thing and expect new results? Maybe it's time to try something different. It's literally the only thing we haven't tried. We've done everything under the sun to make a difference. ERA? Check. Bloodthinners/steriods? Check. Hysteroscopy? Check. Thyroid? Check. At our second opinion in the summer, this was one of the things the doctor mentioned: transferring two may help. It could be that one doesn't secrete the necessary somethings to induce implantation but the other does (clearly I didn't catch all the medical jargon) which may help implantation. If she, as a medical professional, is convinced it can help then maybe it's worth considering.
I took the liberty of creating a simple flowchart for this dilemma.
I don't want to end up with severe complications that could have been avoided. I'm worried about losing all the embryos and being left with nothing. I'm also at a point where I'm ready to try anything for the sake of building our family. Who's to say they'll even both stick? We don't have a great track record for that. If we transfer two and only one sticks and becomes our baby I'd totally consider that a win.
I don't want to deal with this clinic anymore. I hesitate to make a change but more than that I don't want to leave while there are embryos in their care. I keep saying that as soon as we're out of embryos we're out of there. If we transfer two then regardless of the outcome we have no strings tied there anymore. We're free to chose another clinic if we so desire. The same is true if we transfer two but one at a time. The difference is the real issue of fighting against treatment fatigue and trying to hold on to stamina to keep going after continued failures.
I feel like we'll only know the right answer once it happens and we're able to see it with 20/20 hindsight. Until then, we get to weigh the pros and cons and hope that whatever we choose has the desired outcome. When discussing this with my husband I was grateful and relieved to come to a decision we're both comfortable with. In a situation where so much weighs on decisions we need to make, it's a blessing to be on the same page with regard to what to do. At the very least we know we're doing everything we can with the information and tools at our disposable.