Low fetal heart rate

I had my first ultrasound today, we saw that I’m 6 weeks. The babies heart rate was 87. My dr said that I will most likely have a miscarriage since the heart rate should ultimately be around 110 by now and started preparing me for what’s to come. I have a “viability ultrasound” in two weeks. Has anyone had any experience with something like this?

I was also wondering would a decent amount of caffeine help the babies heart rate, since it makes our heart rate faster?

TIA.