Hmm... I would generally say no, but hollywood has fucked up shit.
J-Lo had that movie where she had IVF and then met that dude and all that shit.
Not "exactly" the same thing, but still similar.
I guess if you meet someone and you don't realize you're pregnant, it's fine... but of course if you ARE pregnant and you know it (and aren't showing) then you should probably fess up and just let the guy know so he can decide to stay or go.
Trashy seems harsh, but it does typically show a poor state of mind.