We all have that pregnant or not but it is more noticeable when pregnant. It's a major artery that runs through your abdomen and it is your own pulse you are seeing. good luck
It could be high blood pressure. Talk to your doctor about it.
Its just your heart beat from how much blood your body is pushing thru. I had it happen to me. Im pretty sure its normal but you can ask your midwife or doctor if it is normal if you want to relax and not stress. But im pretty sure it is normal :) just stay calm. Have a Blessed and safe pregnancy <3