The megastar is over in Lake Como, Italy with her husband Tom Ackerley ... and she pretty much announced her first pregnancy to the world when she exposed her bare midriff while getting on a boat.

Check out the gallery ... Margot and Tom are super careful boarding the boat -- they've got some very precious cargo here -- and they both can't stop smiling.

In case you missed it ... once the photos were snapped and first published Sunday by Daily Mail, folks went crazy with pregnancy rumors online and PEOPLE later confirmed the pregnancy.

Unclear if the "Barbie" star is expecting a little Barbie or Ken ... but it looks like she's pretty early on in her pregnancy, at least judging by these images.

Remember ... Margot and Tom, a film producer/actor, met way back in 2013 while working together on the film "Suite Française" and the following year they started dating.

Margot and Tom quietly got hitched in 2016 ... and now they're starting a family.