Paralysis

"...she'll be totally crippled!"

You baulk at her insensitivity. "Crippled how, like losing your legs?"

"No, idiot! Totally crippled! As in you'll never be able to move again!" She tuts at your apparent 'stupidity'. "Except for your eyes and internal stuff, obviously."

You are utterly incredulous. "You truly are a horrible bitch, Mandy. You want to create a child and take away its mother's ability to care for it all at the same time?"

She laughs dismissively. "Oh, I highly doubt you'll make it to full-term, don't worry. Once you go limp, your body will be our plaything, after all. You'll see everything, feel everything, and be able to do nothing."

So that's the real goal. She just wants to turn you into her living puppet.

You've no interest in doing the same to her, but if you refuse...