Oh yeah. I got a rash real bad it started on my chest and spread to my back and stomach and up my neck! It looked like hives. I stopped taking my prenatal vitamin and switched to a regular multivitamin with similar vitamins/minerals + a calcium/fiber supplement and it SLOWLY (like a month) went away. It has not come back. My stepmom had the same thing from vitamin b supplements when pregnant. Try switching up vitamins if you can

Could dermatitis but just got to figure what is causing it 

I get this on the back of my calves every winter and sometimes the summer depending on how dry the air is. I'm pretty sure mine is eczema but haven't gotten it tested. I used Vaseline triple therapy lotion and in two days it clears up. I've read that dry skin is common in pregnancy though.

Is it eczema? I got it really bad on my chest with our son and now that we're expecting again it's starting to flare back up. Hydrocortisone helped to clear it up for me.