Is measuting fetal heart rate in first trimester dangerous?

monika

Hi, due to previous miscarriages I had two early scans at 6w4d (private) and 7w3d (EPU). There was a heart rate and everything looked good but they didnt want to measure the heart rate. I was told it is dangerous as it creates heat and can cause damage to the baby. But this forum is literally full of heart rate measurements at 6-8 weeks. So is it dangerous or not? Thanks!