Elevated heart rate

Hi everyone,

I'm currently 30 weeks pregnant and for a few weeks now have had days where my resting heart rate is around 120bpm. For the past couple of days it's got a bit faster at 126. This is when I am literally sitting on the couch. I know as soon as it comes on as I can literally feel my heart pulsing through my chest and pulse points and I start to feel really quite light headed and exhausted. My iron is slightly low and I know that maybe has something to do with it. Just wondering if anyone else has experienced this and what were you advised? Thanks in advance! ☺️