When to tell my fiance?

April
So a few days ago I got my BFP and normally I would be so eager to tell him, but since this past September I have had 2 miscarriages, both were between 8 and 9 weeks. First one was September 27th and the second was December 31st. my OB ran all types of tests and there is no actual reason why I have suffered these loses. I was given the "go" to try again whenever I was emotionally ready. But this time we weren't exactly trying, but we also weren't using any protection either, I'm just looking for some insight, I want to tell him but I also don't want to stress him out worrying about me all of the time... what would you ladies do?