How do you act around your friends struggling with infertility?

I have a sis in law I talk to every day about who has been trying for 1.5 years and they are currently seeing a urologist. Two other friends who have tried for around 3 years and each had one miscarriage and a cousin and church friend who have also been trying. I feel surrounded by infertility and almost guilty to be having my 3rd. I also don't know how to talk to them and dance around the baby subject. I'm sure I'm not the only one! My sis in law admitted to crying when I gently broke the news to her over message. How do you respond to those hurting while you have excitement?