Eva Mendes Pregnant -- She's Got Something to Hide ... Ryan Gosling's Baby!!!

So this is ironic ... Eva Mendes -- now the envy of every woman on the planet and a sizable number of men -- is going to gargantuan lengths to hide the fact that she's carrying Ryan Gosling's baby.

Eva was leaving a parking structure Wednesday in L.A. when she ran into a photog ... hours after news broke she's 7 months pregnant -- allegedly 7 months.

She went through contortions to hide the baby bump, using a Birkin bag, scarves and everything else within arms reach to obfuscate the money shot.

Wear it like a badge of honor, Eva.