Concerning to how aids is spread in having .We all know the main way of catching aids is through now?

they say just by having once you can catch the disease because you may not be promiscuous but your partner might be at least how many partners you think it takes to have with before you catch hiv.say that a couple already had with other people and they both take a pap smear test and they find their free from stds and aids how does the doctar know its safe for them to have ?I mean suppose that last time they have sex they catch an std or something.Could doctars tell persons sex history