One friend told the New York Post newspaper: "She is so excited she is going to be having a boy. She says she has never been happier than now, when she is pregnant."
Halle previously revealed she didn't want to know the sex of her baby before the birth, saying: "There are so few genuine surprises in life anymore that, why not have a huge surprise? And I like fantasising one day that it's a girl, and one day that it's a boy."
The 41-year-old Hollywood star also claimed she loves being pregnant so much she wants to try and conceive another baby "immediately" after she gives birth.
Halle laughed: "There's just one baby at the moment, but we're hoping, immediately after this one, to do it again!"