Halle Berry -- PREGNANT!!!

Halle Berry is pregnant with her second child ... TMZ has learned.

Sources connected with the actress and her fiance, Olivier Martinez, tell TMZ ... Halle is around 3 months pregnant -- based on the pics and some other facts we know ... she may be a little further along.

What's more ... they know the sex. It's a boy.

This could explain why Halle and Olivier were so upset when paparazzi got too close to her earlier this week at LAX while she was carrying soon-to-be big sister Nahla, who is 5.

It's definitely worth noting ... Halle is 46, and Olivier is 47.

Check out this pic of Halle at the Oscars (above) in late February. A source connected with the actress tells us Halle was feeling sick and was complaining she had gained a little weight. We're told days later she found out she was pregnant.