I read about it on an article, app name is "Baby scope app", and had to try it.. It's using the iPhone microphone to pick up the baby's heart beat! brilliant! and for me it works :-)!!! Obviously it's not a "Doppler" since it's using the microphone to pick and enhance the heart beat sound, but still , I can hear it!! Had to recommend it, although , must warn from the downsides... If you use it in a loud environment, it might hurt your ears (so use it only in a quiet room), and if you are a "stressed" mommy to be , you should avoid it - it's fun to hear baby's heart beat (even recorded a sample and played it to my sister that came to visit us) , but if are likely to get stressed because you can't find the heart beat, please DO NOT use it since it's only an iPhone microphone, so no point of taking it too seriously.. XX
It said so in the app description that the app is targeted for last trimester of the pregnancy , mainly due to baby's heart beat size (as the baby gets bigger, his heart beats becomes louder...)
Re: Doppler app! for iPhone... love!
"Beanie" Natural 7w MC 11/21/12
"Nole" stopped growing at 7w3d D&E 2/11/13
Diagnosed with MTHFR and Factor V Leiden on 4/3/13
Due with RAINBOW GIRL 2/10/15