She can feel vibrations through her feet and her hands. That's how she learned how to metal bend by touching the metal with her hands. Basically with her whole body as long as there are vibrations she can feel them. But no she can't do ultra sound. Course if the baby produces a heart beat or something, she could feel the baby, but she wouldn't know what it looked like. I like to think of what she does as what we do with heat vision and heart sensors in our guns. She gets a blurry understanding of what is going on around her and who the people are but not all of it.
Her world probably looks something like this to her -
This being heatvision. Her's is vibration vision.