How very sad for your friend. Please call her. Even just to say "Hi, it's me, & I'm here if you need me for anything."
November of '01 I attended my monthly Ladies Club Church Meeting. At the same table sat a girl who had just lost her baby. (He was born with multiple heart defects ~ which they already knew about...lived for 5 hours & died in his mother's arms.) I had just delivered a beautiful healthy baby boy a month after her tragic loss. At the meeting, all my friends were asking about the baby & wanting to see photos & I was happily telling them all about my newborn, until I looked at "her" face. I was then mortified that I even spoke of my newborn! She was choking back tears, which led us all to do the same. She excused herself & sat at a different table. I went over & apologized & hugged her & explained that I was so sorry for her loss, but as guilty as I felt, I was so excited about the arrival of my little miracle. She said she understood but the wound was so fresh that she just couldn't handle it. Well, it has been over a year now. We do talk about her "Robbie" almost each time we see each other & we cry together too. But she has moved on & knows that her son is in a much better place. He's not suffering & he's waiting to someday be re-united with his loving mother again. They are thinking about trying to have another baby soon too. They currently have a 4 y/o. There is healing but it takes a while. Personally, I don't think it's ever a "full" recovery after such a loss but I'm happy to see that she is healing.
Sorry that was so long.....I just know how you're feeling. Been there ~ November '01. Just let her know that you're there for her. If a card would be more comfy for you, then by all means send one, but just DON'T DO NOTHING! That would really be a tragedy.
God bless her & help her find strength in these coming days.