loads of people will disagree with me but i really dont like dopplers. the one i hired caused me nothing but worry after i couldnt find the HB and the stress from that did me alot more harm than any reassurance it could or possibly brought. my consultant also tried to find the HB at 18 weeks and couldnt (although im not entirely sure he was looking in the right place as he seemed to be going too high up) and i had to be scanned to check everything was ok, i was a nervous wreck.
on top of that alot of ladies can become dependant on them for reassurance and it could mask a potential problem later on, this is why its important to monitor movements aswell, as even if HB is heard if movements have stopped or changed it still needs to be checked out once u are at a stage when u are kick counting.
not saying any of this to worry anyone, just my view on why i dont like them and why alot of MW's dont recommend them being used at home