Stretch marks and dating

Stephanie • CMA at the moment and going to Nursing school
Hello my name is Stephanie, I've been dating a guy for a while now and it's getting to the point where we would like to get intimate but I am very self conscious about the stretch marks I have from pregnancy and I also haven't told him I've had a baby because my son passed away when he was 3 months old, it's not an easy subject to bring up... How do I tell him about this?