When I happen to be conducting my significant and considerable business in a public space that demands I observe a pregnant woman, I am overcome with a barely-controllable urge to point in her general direction and exclaim, “she had sex!”
But then I consider that I haven’t eliminated other possible explanations for her condition. And I wouldn’t want to look foolish.
HR Lincoln 
Well, it’s usually a safe guess that sex (as in intercourse) was involved, but you are right, there are other ways it could have happened, most likely in-vitro fertilization. Or (hopefully not, because the very idea of it has horrified me my entire life) immaculate conception. Gah.
But. But. But maybe you’d start some sort of pseudo-spanish-daytime-soapopera-type situation. That would be great, albeit unlikely.