A true Fetal Doppler, like the one used in your doctor's office, does work and works off of ultra sounds waves.
If you mean the "Bebe Heartbeat listener" thing that you can buy at Babies-R-Us or Wal-Mart than honestly it depends on you. Some women say they do and other women report them as being a complete waist of money.
You can rent or purchase your own doppler like the one that is used in your doctor's office but it shouldn't be used to often since it DOES use ultra sound waves which with prolonged exposure can change the temperature of the amniotic fluid.
You could also get a Fetal Scope which works much like a stethascope and does NOT use ultra sound waves.
at 3:24 PM on Jun. 1, 2009
The first reply is totally right. We bought one at Walmart and ours did work, it was like someone was tapping a stethoscope. We took it back anyway because we were so far along that counting kicks worked fine. I don't know how well it would work early on though.