K.,
will be praying that all is fine with your friends baby.
The best thing you can do is just be there. Ask her if you can help cook dinner for them or help clean up or run errands. Just let her know if she wants you to pray with or just to vent or yell and cry, you are there and will hold the box of kleenex if needed.
Many of us (me included) are fixer, we want to do something to make it better, and it's hard to just sit there. Many times that is what our friends really need, just someone to be there.
If the test do show something, then offer to help watch her little one if she needs to get away for a few minutes, or needs time to research information. Or offer to do the research and then give her the links or what not...
And help with meals if needed.
Hope and pray for a good report.