Margot Robbie's about to give birth to her own little Barbie or Ken ... 'cause the megastar's pregnant according to reports!

The actress and her husband Tom Ackerley are expecting their first child together, PEOPLE reported Sunday ... ending a morning full of speculation after pics of Margot's baby bump made their way online.

In the photos -- published by Daily Mail -- Robbie's carefully boarding a boat in romantic Lake Como, Italy ... and, her top exposed her midriff immediately getting people online talking.

PEOPLE broke their story a few hours later ... saying multiple sources close to the couple confirmed the pregnancy.

The Australian actress and her film producer/actor beau met back in 2013 while working on the movie "Suite Française" and started dating a year later.

They quietly married in 2016 ... and, Tom's been at her side ever since -- supporting her on the red carpet during all the hype surrounding "Barbie" last year.

We've reached out to reps for Robbie and Ackerley ... so far, no word back.