In a bid to recover, Kate, 30, may spend this year's Christmas with her parents instead of attending the Royal Family's Christmas get-together at Sandringham, Norfolk, The Sun reported.
Kate spent three nights in hospital this month with hyperemesis gravidarum and experts say she may suffer for several weeks.
She has been recovering by staying with husband Prince William at Nottingham Cottage, the home they share in the grounds of Kensington Palace.
A royal aide said it was "too early" to say if the Duchess of Cambridge would travel to Sandringham.
"The only Royal Family we would definitely say are staying are the Queen and Duke of Edinburgh," the aide added.
The Duchess spent her first Christmas Day at the country estate last year - when 3,000 people turned out to see her.