How do I stand up to my employer?

Did you get a note stating the health risk of having you at work while ill on top of being pregnant? I'd submit that to her as well as your higher-ups and they'll have no choice. 

 if your doctor or the ER doctor gave you notice thenn I don't see a reason why she is making you go in...go higher up with the notice

Quoting Pandapanda:

Did you get a note stating the health risk of having you at work while ill on top of being pregnant? I'd submit that to her as well as your higher-ups and they'll have no choice. 

Number 1, who the hell wants someone sick with the flu working next to them, shedding virus all over the damn place (no offense)

and number 2, rest is one of the most important parts of recovery. if you're not resting, you are putting yourself and your baby at serious risk.

and number 3, what a C U Next Tuesday your boss is.

You might say you need a short-notice planned absence and take the last 2 days off, like a compromise.    Of course, this is IF you feel up to that!
REALLY you should put your health & safety as your top priority, IMO, though.

hugs!    What a hard situation.

:-(

She said "if you can get it covered?"    
   So you can ask to find someone else to do it and if not she gets to.

Quoting blessedmommy864:

  she said if I can get it covered its fine, if not i have to work it.. I just feel like she's lazy and she doesn't want to have to come in and work it herself!