Other people's happy news.

Tomorrow I meet with ex colleagues for a catch up. We all keep in touch a few times a year and I was looking forward to seeing everyone. Today one of the ladies announced their pregnancy. How do I get through lunch with everyone cooing? How do I take part in the conversation? I am happy for her. I just don't know if I can be excited. I absolutely do not want to in any way dampen her excitement. I don't know her journey. Has anyone else successfully negotiated a similar situation?