"It's so difficult to just be," said Williams of the first few months of parenthood.
"I still have moments where it feels like it's not dawning on me that I'm a mother."
It is understood the christening will be held next weekend at the private chapel at Windsor Castle and will be a "very small gathering".
His words are the most candid from any member of the Royal family in public on the topic to date.
Fifi Box has welcomed a second daughter.
The texts between the two celebs have mums around the world chuckling.
A new poll has found that fathers experience 'daddy-shaming' too - and all that criticism is having an impact.
The Duke and Duchess of Sussex have shared a new photo of their six-week-old son Archie to celebrate Father's Day in the UK and the US.
Members of the Royal family turn out in force to mark the Queen's official birthday at annual Trooping the Colour celebrations.
From a sip of wine to apparently ceasing to breastfeed, celebrity mums are constantly in the firing line of mum-shamers.
Nike said it would waive performance-pay reductions for 12 months for athletes "who decide to have a baby."