The 30-year-old said it has always been her dream to have a boy first and then a little girl so he'd be the big brother, reported Contactmusic.
"He says, 'Mummy, I want a baby sister,' every day. I say, Give me another year or two. I used to say when David Jr is four, but he's almost four now. So maybe when he's five or six, because this is coming too soon," Hudson said.
The actress raises the baby boy with fiance David Otunga. Hudson and Otunga got engaged in 2008 after dating for several months and will soon tie the knot.