OP here.
Yeah, it did cross my mind that maybe there were health reasons related to the baby, or the circumstances of the pregnancy that might be contributing to her behaviour. It would certainly make me feel much more sympathetic towards her and honestly I was worried.
However, the night she announced it at the party (after everyone had congratulated them including me) we spoke briefly in the kitchen with no one around and did what I thought was the usual and correct thing of hugging her and asked if she was happy, was her husband happy about it (because one of the things she had confided about in the past was that her hubby wasn't keen and she didn't know if she wanted to either and if he didn't then the decision was made for her really), and she said they had both discussed it, that they decided they wanted children and decided to try and she got pregnant straight away and found out early October. I told her it was awesome, can't believe you didn't tell me! and hugged her again. I also overheard telling people about the scans and how everything was perfect.
So I guess it can't be that!
However, the more I think about it the more I think it might just be her personality and the hormones making it worse. She has always been quite judgemental and easily hurt and I've heard about when other people have hurt her but it's never been directed towards me so maybe I was too slow to see. Maybe now she is just really over-reacting to everything? I honestly don't know! Maybe she heard 'can't believe you didn't tell me' and didn't hear the excited tone or the smile on my face?
Or she just really is one of those people that changes friends with life changes.
Neither my friend nor her hubby were at our church group again last night and no one has seen or heard from them either. Another girl emailed my friend ahead of last night to ask if there was anything they wanted us to pray for but received no reply....