I don't know if they are common, but they do happen. And I think you can use a doppler at home in the second trimester. I will definitely get one if I ever get into a second trimester. I understand what you are saying about having symptoms of m/c. Two out of three of my m/c's were missed. I found out when they did an u/s and there was no hb. So I'm sure I will be anxious every time I go to the doctor with a future pregnancy.