30 years old and scared to tell my mom that I’m pregnant

As the title says, I’m a 30 year old woman and I’m so on edge about telling my mom that I’m pregnant.

I am married, have three other children, have a good paying full time job, my husband also has a good paying job and we own our own home. We have two cars and never have to ask for help from anyone for anything...not financial or otherwise.

However, my mom does this thing where I mention trying for a baby and she’s so excited and supportive and then I announce the pregnancy and she suddenly gets super negative about the entire thing and tears me down my entire pregnancy.

My husband thinks I should just not tell her until I cannot hide it anymore. I don’t feel right about keeping it from her but I don’t know if I can deal with the stress again. How can I talk to her about this? What could be her reasoning for behaving this way? I don’t understand it. It is very upsetting for me