Newly- They're safe. I realize there's a lot of articles floating about that do not support the use of fetal monitoring or doppler/ultrasound use of any kind, but unfortunately, the data is not truly supporting that there are any real dangers to any of it. A lot of the naysayers are buying into a lot of pseudoscience, and honestly, if it puts your mind at ease, it is worth it. I used my doppler daily during both of my rainbow pregnancies, and literally saved my sanity. That being said, I was unable to find the heartbeats with either child until I was about 13-14 weeks along.