What to say to someone who is expecting a child with birth defects?

Hi,

I'm sorry to everyone who went through a though time. A friend of mine also is going through a tough time. She is expecting a child with birth defects whom might not live long and if he does it will be with invasive procedures probably. I don't know what the defect is called yet, but I just want to prepare on what to say and not to say. Do I say congratulations on the pregnancy or not? I would love some advice. Thank you.