Saliva - Sorry I Might Be Naive

Okay, so I was reading in the Glow topics a few nights ago, and read something I had never heard of. Does saliva really affect sperms ability to be 'effective' (for lack of a better word). Does that only apply to giving him oral? Or does it apply if he gives you oral first (my husband loves this and it's a usual thing)... I am honestly wondering if it's true, because I would like to know if that is affecting my fertility! (Medicine is saying nothing is wrong).