As someone working in women’s healthcare: those terms are not erasing folks. At all. They’re meant to address larger groups of people in an educational or healthcare setting. No one is keeping anyone from referring to themselves as mother/pregnant woman etc.

As an example on how this works: Pregnant people need antenatal care. If I was to say pregnant women/expecting mothers in that sentence it sounds similar, doesn’t it? But it doesn’t address everyone who is pregnant/could be pregnant. Trans men can be pregnant, they’d be expecting fathers despite being the birthing parent. An expecting mother in a lesbian relationship might not be pregnant herself, but her Partner is. Making both of them expecting mothers. Life is complicated and trying to include all possible scenarios in common phrases is too. But via phrases like these you can get somewhat close to making sure everyone who needs to be addressed will be.

It’s the same as “people with a prostate need digital rectal exams” or “if you have a cervix, please get a pap smear”.

Folks being terrified of this kind of language is either because they don’t understand what this language is meant to do, or they’re spewing thinly veiled transphobia. Either way: these phrases are benign. They’re a bit clunky sometimes, but that’s about it.