It is so kind of you to ask this question! You are a good friend.

I have had two miscarriages. The first was my first pregnancy, and it was the hardest. My advice is to say very little beyond "I am sorry" and "I am here to listen whenever you need to talk" and "I love you and my heart breaks for you." Just hold space for your friend.

Really, anything people said to me to make me feel better had the opposite effect: "You can try again", "This wasn't really a good time to have a baby with your busy work schedule anyway, right?", "Someday you will have a baby, I just know you will."

I have since lost my mother, and I truly appreciated people's words of love and support, no matter how awkward, and knew they were coming from a good place. With the miscarriages, it was different -- I was particularly sensitive about the words people used with me. Strange! Maybe it's just a matter of accumulating more life experience and loss.