I dont know what to do...?

so... i took a prego test this morning.... and its positive. i have really bad ovarian cysts and the doctors told me that i am able to get prego but the chance of me carying full term is only 80%. i have had 3 miscarriages before, so i am expecting this pegnancy to be the same. with all of my past 3 pregnancies i didnt carry past 3 months. should i tell my boyfriend? or should i just wait to see if i miscarry again? i dont want to worry him about it right now. plz help. i dont know what i should do.