Period sex

I recently went to my bf house and I started my period that day as well. I enjoy giving him pleasure so even thought I was on my time I still wanted to give him a treat... after a little while he mentioned sex and I personally have never had it while on my period nor have I been disgusted by the thought of it but has anyone else done it? I feel like it’s not very common to do it... is it normal have blood go down your legs during?