When someone you know has a preemie it's a hard time for everyone. The excitement, pomp and circumstance that usually surround a birth is absent. It's hard to know what to say to help the parents because you know nothing you say will make them feel better but you also don't want to say something stupid and make them feel worse. Here's some help:
-First and foremost, if you don't know what to say, for the love of God don't stay quiet. Nothing made us feel worse than people who just didn't say anything at all. In hindsight we know it was because they didn't know what to say but in the moment it felt like we were either ignored or Munchkin wasn't being celebrated. Yes he was early and it was scary but he was still born and that's still reason to celebrate. If you don't know what to say, say that! "I don't know what to say but congratulations and he/she is amazing. You are so strong and let me know if you need anything."
-Do NOT lead with "oh my gosh, he/she is so tiny" and leave it at that. The baby was early, the parents know the baby is tiny and don't need that constantly pointed out. However, if that's part of what is said it's okay. So tiny and cute, so tiny and feisty, so tiny and look at all that hair! These are all okay, pick a second adjective though and don't just stick with tiny.
-Sometimes just the offer of help means the most. The parents may or may not take you up on the offer but they'll know you're there if they need it. Trust me, some of the people I remember the most throughout our whole ordeal are the people who offered some sort of assistance every time I talked to them. There is one friend in particular that sticks out for me. Every single time I talked to her she would offer a shoulder to cry on. Every time I logged in to Facebook I would have a message from her reminding me if I needed to talk she'd be there for me. I can't explain to you how much that still means to me. I never took her up on it because I wanted to just crawl into my shell and put on a brave front, but I thought about it almost every day.
-DO NOT forget they had a baby and there is cause for celebration. Send a card, flowers, balloons, or whatever you would've sent had the baby been full-term. Don't be overenthusiastic about the birth but don't be too depressing either.
Above all else, be a sounding board. You won't be able to honestly feel what they feel or know the emotion that goes into it. You won't understand a lot of the medical things that are said. But the best think you can do is listen and be a shoulder if that person decides to open the flood gates to you.