I've been thinking a lot about this subject. In particular, I've been thinking about some friends who have gone through this, and I always think of things to say after the opportunity has passed. Well, this is what I would say to myself, at least. Take from it what you can. And hopefully you will find something that will help.
First off, this is a horrible experience to go through. I don't wish it on anyone. But the fact is that miscarriages are so common, yet when you are going through it, no one knows exactly what to say, including me...who has had two miscarriages. I think in part, because when someone tells you they are having a miscarriage, it catches you off guard. Unlike when you loose a love one, a grandparent, parent, friend, a child, there are no funerals for miscarriages. Something I wish I had done when I had my miscarriages was to have my own private "funeral" for that lost pregnancy. I wish I would have written a letter to that unborn child, placed that letter in a box along with some sort of trinket and buried it in my backyard, along with a flower/plant. I think having a "funeral" would help the grieving process, as it does for a funeral of a loved one. I also think that if we had come to the conclusion that infertility was permanent, that trying fertility treatments would stop, and the hope for a biological child had been lost, then doing a "funeral" would have been my next step.
Second, when you are experiencing infertility, and have had a miscarriage, or several miscarriage, the automatic thoughts are: "your body is fighting against you", "your body is rejecting pregnancy" ,"your body is failing you." ....etc. Looking back, I wish I had changed my way of thinking on this. (Though difficult to do.) I wish I could have told myself instead this: "My body wanted that pregnancy just as bad as I wanted it, and it did everything it could do to keep that pregnancy. My body was expressing it's own way of grieving when the pregnancy was lost through physical pain." For whatever reason, and God only knows why, that pregnancy was not to be. And trying to chase reasons why can just become torture. Don't look back and ask yourself what "you did" to loose the pregnancy. Truth is that you didn't do anything wrong. My first miscarriage, my body did not want to expel the pregnancy, and we found out via ultrasound that there was no heartbeat. I took the medications to expel the pregnancy, and still my body did not want to loose the pregnancy. My body wanted to be pregnant. Finally we did a D/C. My second miscarriage, and the hardest emotionally, was with our first attempt with IVF. I had a molar pregnancy, or an empty sac. It was like a slap in the face from God saying that there was no baby for you. In actuality, I believe that was what Satan wanted me to believe. (Obviously, because God gifted me with two babies.) It was a weird experience because my body did not expel all of the embryonic tissue, and what was left over continued to grow, forming that empty sac...Again, looking back on this, MY body wanted to be pregnant. My hormone levels continued to go up, and though it was torturing me to get tested, giving me false hope seeing my hormone levels rise, I knew it was a failed pregnancy. I had to do a D/C again. It was an awful experience, but looking back, I can see and appreciate how my body was trying to work FOR me. Now, I know there are medical reasons why pregnancies don't work out, such as digestive problems, or what have you. Trust that you Doctor is doing the best they can to find out what is wrong. If you get the feeling that they aren't trying to find out what's wrong, seek a second opinion. But know that our bodies were made as females to have babies, and by having a miscarriage, know that you CAN get pregnant. Though it is hard to believe, especially when you are infertile. But Believe that your body can do this, love your body for what it already does for you....
Third: You know what it is like to have a positive pregnancy test! Some women never experience this beautiful moment. Relish that moment. What was it like? You knew the joy (and fear) that comes from this. Appreciate that you had this life experience. Although the outcome did not turn out as you had hoped. Take a moment and write it down. Maybe include it in the letter for the "funeral."
Finally, let yourself grieve how you will. It may take months or years to get over this. It is different for every woman. If you want to go drive out to the middle of no where and throw rocks and yell, then do it. Releasing that negative energy from your body is actually good for your body. Allow your body to release the anger. Try not to hold on to it. And Pray to have that weight lifted from you. I found my way to release my anger through exercise and yoga...and a lot of crying. Do what works for you.
Anyway, I hope that helps anyone going through this.