Heart palpitations

Saw a cardiologist today for heart palpitations. She assumes it’s from my hypothyroidism. (Thyroid levels are now normal) I am 35 weeks and they don’t have an appointment open until end of next week to put a halter monitor on me to monitor my heart. Then it’ll take a least a week for them to review the results. At that point I could possibly go into labor! I’m really worried about how this could effect me during labor. My cardiologist asked if they planned on inducing and looked surprised when I told her no. I’m getting a little scared that something could go very wrong with my heart during the stress of labor and they don’t have all the data they need ahead of time to prepare properly! Anyone else experience heart palpitations during pregnancy or have similar experience? Wondering what I should ask my OB at my next appointment.