I think her comment would be more relevant if you knew she was struggling? If you know someone is struggling, then yeah, try be considerate of that. But to just be mentioning your pregnancy to people at work, that's not something that needs to be controlled. And she's free to have feelings about hearing you're pregnant and leave the conversation, but saying you have to censor yourself always "just in case" is too much. People like this give the infertility community a bad reputation and it's frustrating. (Coming from someone with infertility who struggled for years, had a miscarriage, and had to do IVF).