Resting heart rate 146bpm

Melissa • 26. I love my husband and so thankful for my friends & family. We're expecting our first little one.
I am currently 29 weeks 2 days.. I've been having funny episodes every day or so for the past month where my heart rate spikes to between 120-146bpm while sitting. I then have to lay down and wait it out. Could it be related to my baby or should I see a doc? It comes down to 80-90bpm within 10-15 by itself.