Nicole and Keith are already parents to Sunday, 10 and Faith 8 and despite the mother-of-two's longing her husband "isn't on the same page".
"There was a time he thought he might like to have a boy, but he doesn't want to take previous time away from the girls," adds the insider.
"Their careers already force them away from home for so long. He's hoping that Nicole will come to see that things are better as they are."