Sex during early pregnancy; good or bad?

Hello glow nurture community. 
My fiancée and I have recently found out we're pregnant and believe to be around 4.2 weeks. 
​This past January, we endured a very traumatic miscarriage due to a food allergy. We found out 5 days ago we're expecting again and last night was the first time we tried to be intimate and I couldn't do it; we stopped before we even really started. 
​My fear is sex triggering another mc. I have 2 children and know this is silly to think, but the fear ends up taking over. 
​I guess I'm just looking for reassurance as this fear has deminished my sex drive and has made me unable to allow myself to have sex with my fiancée! 
​Has this happened to anyone before?