The 31-year-old said that she wants to grant him his wish, and would like a daughter herself, reported E! online.
"I definitely want another baby. I want a little girl so bad and every day David Jr reminds me, 'Mommy I want a baby sister. I want a baby sister'.
"And I said OK, maybe when he gets 4-years-old, but he is 3. He is almost 4 now so maybe when he gets 6 or 7 because...3 and 4 comes too fast," Hudson said.
The 'Think Like A Man' hitmaker has been engaged to World Wrestling Entertainment (WWE) superstar David Otunga since 2008.
He is all set to branch into acting with a role in 'The Call' and Hudson said that she has a new nickname for the wrestling star.
"We call him 'Curtains,' because when he got the role he was like, 'Curtains for everybody. He's so excited. I can't wait to see the film ... He's super excited about the project coming out and he got to play an officer ... I just got to see the preview for it... Look out, curtains for everybody," she added.