I find that it’s so easy to over-analyze in this process, inevitable leading to anxiety. I’m also tempted to consult Dr. Google and we all know how that turns out. So I’ve been trying to not over think it, but the one aspect of my upcoming FET that has really got me in knots is the timing of the transfer and my Endometrial Receptivity Assay (ERA) results. Learning just enough about the ERA test and implantation to make me dangerous, I’m struck by just how small the window is for implantation. Since I only have one embryo, I know we have to get the timing right for success. When the timing is off, that’s when perfectly normal, healthy embryos don’t make it. Sure there are other reasons FETs can fail, but this is a big one. And so, I’ve been worried.

Let’s talk ERA testing and implantation. Here are the basics. Estrogen help us grow a nice plush lining. Some women do a natural cycle for this and others do a medically controlled one. If you’re going the medical route, there are many different protocols to help you get there. Mine included 2 shots of estradiol weekly for about 6 shots total prior to transfer. My nurse explained that while estrogen helps build the lining, progesterone helps the lining stay put, so days before the transfer I’ll start progesterone in oil (PIO) shots. But it’s a lot more than that, really. Progesterone actually changes the make up of the lining and helps the receptors there activate.  Now here’s where it gets scary. Those receptors are only active for a short amount of time and then they close off. An embryo can only implant during that small receptive window. So the timing of the transfer is key, and that’s really based on how long progesterone has been in your system.

The ERA test is a relatively new one to hit the infertility treatment scene. To do the ERA, you do a mock cycle – including medications and all – but instead of doing the embryo transfer, they biopsy your lining. My RE did 2 biopsies in one mock cycle – a biopsy on day 5 and another on day 7 – to ensure that we covered the most likely receptive time frame. If the first biopsy comes back receptive then they don’t bother testing the second. But if the first is non-receptive then they can test the second sample to see what’s going on. I was glad they did 2 biopsies in the same mock cycle because it saves time  (and money) from having to do another whole mock cycle for a second biopsy if the first one fails to find the right day.

In my case, the first biopsy came back pre-receptive – meaning my lining wasn’t quite ready yet – and the second biopsy came back post-receptive. The laboratory that did the testing recommended a certain number of hours of progesterone that would get me right into the middle, which should be my peak receptive time. Based on this, I’m supposed to start my PIO shots at a very specific time and have my transfer at a specific time on day 6. Those results have literally been haunting me.

There were 2 things that worried me:

1. I’m worried about doing a transfer on day 6 since for my first IVF we did a fresh 5-day transfer, which obviously worked because I have a daughter. So is changing the day really a good idea?
2. I was really hoping one of the biopsies would come back “receptive” rather than pre- and post-receptive because,  to me, that seems like guess work. Having a biopsy be clearly receptive would seem like more of a sure thing. Maybe my thinking was wrong here, but I was worried.

Now I haven’t seen my RE since my biopsy, and won’t see him until the big day, and the nurse gave me my ERA results. She assured me they were accurate and I tried to accept that. But here we are one week before my FET, and I couldn’t stop thinking about it. Today I went in for my last blood draw before the transfer, so this was really my last chance to ask questions in person before the big day. I went in to get my blood drawn, and to my surprise there was my RE standing there looking at some files. He’s rarely ever out of his office or the exam rooms, so this was a rare opportunity. I asked him if he had time for a quick question even though he was clearly busy. He said yes and not only took the time to fully answer my questions, but he even drew me a graph. I love this guy. And I feel so relieved having my questions answered and getting a better understanding of this complex process. So I wanted to share.

He drew a normal bell curve and explained that it represents how many receptors are active in the lining. The more receptors that are active (represented by the highest peak of the bell curve), the better chance an embryo has of implanting. The ERA results focus specifically on finding the peak window of receptivity – the optimal receptivity. This could be day 5 for some women, or other days like day 4, 6, or 7. My results gave a peak window on day 6, but there are still receptors active on day 5 (which for me would be on the right side of the bell curve where the line is lower), which is why my last IVF transfer worked. ERA doesn’t test for the whole bell curve – it’s aiming for the peak window. So he said, that this time I’ll have even more receptors active than last time so we will be giving my embryo an even better chance of implanting than we did the first time.  That cleared up question #1 for me and made a lot of sense. Then he explained that the test is able to accurately calculate my receptive window even with the pre- and post-receptive findings, so they purposely space out the biopsies by 2 days (rather than doing days 5 and 6) to capture the best window. He said he is very confident in the results and that made me feel good too because he is great at what he does and I trust him. I’ve also read about the high accuracy of the ERA in research studies. That gave me peace of mind on question #2 also.

My RE also gave me a nice analogy. He said that the receptors in the lining are like a field of flowers. The more flowers you have open, the more likely your baby is to implant. At first, only a few early flowers begin to open. Implantation can occur but it’s less likely. Shortly thereafter, the whole field bursts with life and all the flowers are in bloom. This is when there is the greatest chance for implantation. Then most of the flowers begin to fade, while a few hold on for a bit longer, and implantation success dwindles. The ERA test tells you when your whole field is in bloom. A pretty thought, isn’t it? I think I’ll use that visualization on transfer day, and the days after as my embryo continues to nuzzle in, Goddess willing. I can’t help but think that someone was looking out for me today and helped time things perfectly so that I could ask my RE these questions. Now I’m going into the last stretch with a renewed sense of calm and confidence. I finally feel excited!