My wife had risky pregnancies. There is cheap professional but portable ultrasound you can rent. We had one for like 6 months each time (3x). It is a lifesaver when you know baby is OK and you don't have to rush to emergency for every little thing. Otherwise we would go crazy. Since we monitored at home blood pressure and sugar level, we were really good and not as much in the dark as we would be.

You could hear baby heart and also blood rushing to placenta. And those have distinct sounds and places you could check.