Heart rate reduced between ultrasounds ?! Is this normal?

Kaitlin

I had another ultrasound yesterday. 11 w 3 d but baby measuring 3 days ahead. The tech casually said the heart rate looks good at 141 bpm. I’m so happy to see and hear the baby but I have anxiety because 3 weeks ago the heart rate was 171. What is going on ? Is this normal or something I should be concerned about?

I’m starting to think the worrying won’t end till I see this baby !