"Obviously William I've known for quite a few years, and William is such a great person, such a great dad," the father-of-four said at the launch of his Belstaff collection at New York Fashion Week.
"Catherine is exactly the same. She's a great mum and obviously with the commitments that they have, to be a great mum and dad is pretty incredible."
He joked: "They definitely need to get some more sleep before this little one arrives."
Beckham will have endured his fair share of sleepless nights with his four children Brooklyn, 15, Romeo, 11, Cruz, 9, and three-year-old Harper.
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Prince William for one, is likely to be taking heed of Beckham's wise words and getting as much sleep as possible before the baby arrives; following the birth of Prince George in July 2013, he complained that he was suffering from the lack of sleep.
"At the moment, the only legacy I want to pass on to him [George] is to sleep more and maybe not to have to change his nappy quite so many times," William said.
David and Victoria attended the royal wedding and the former footballer has worked closely with William on a number of projects over the years.
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