I know nothing about SB, but it would seem to me that the baby shower should proceed normally. A child with health problems is just as wonderful blessing as a "normal" child (if not more!) and just as much to be welcomed and loved. I would think that the subject should not be avoided but also not obsessed over. The mommy will need extra love and support.
The postpartum period is SO difficult even with a healthy baby - I would think that one really helpful thing would be to have a sign-up to bring meals to the new family after baby is born. Our church did that for us, and it was SO helpful and supportive - I would think it would be essential for a special-needs baby's family.
Also, here's something that we just did at my friend's baby shower, and it was wonderful - it might work especially well for your friend. It's called a bead ceremony. Each guest selects a bead from a bowl and strings it on a wire, and as you go around the room doing this, each guess says a wish or a prayer or a blessing or some sort of loving statement to the mother. I'll print the examples we gave below:
- Encouragement: “You are going to be a great mom.”
- Love: “We are so happy for you.” “We can’t wait to meet your baby.”
- Prayers: “I pray for a wonderful birth experience for you.”
- Encouragement: “God has a wonderful plan for your life as a mother.”
- Friendship: Share a fun memory of -----’s pregnancy, or something especially precious about your own pregnancy, birth, or experience as a new mother.
The beads are then made into a necklace for the mommy to wear during labor and after baby is born as a reminder of the love of her family and friends. This might be applicable to her situation and would be a time for people to acknowledge the baby's condition while expressing unconditional love for both her and baby.
Blessings!!!