The announcement of a pregnancy by another woman/couple tends to bring terrible pain to someone who is struggling with their fertility, or has recently experienced an obstetric loss. It isn’t that they mean ill to the happily pregnant woman, it is more that that her joy makes their sadness feel even greater. It’s a really normal part of the grief.
This article does a great job of discussing this pain from the perspective of a woman who has understands that feeling of hating all the other pregnant women… and then finds herself as one. She finds a way to still have and share her joy, but still maintains sensitivity to all the other women she knows are waiting in the wings, watching and wishing for their own time.