Despite the fact that the royal couple do not know the gender of their second child, punters seem convinced they have inside information, and around nine in 10 bets have been placed on the arrival of a princess.
"The latest odds suggest that Catherine will give birth to a baby girl. She will be born on Saturday the 25th, weigh between 7 & 8lbs (3-3.5 kg) and be named Alice.
"She will have blonde hair and it will be a proud mum holding her as she is introduced to the world's media," one of the punters was quoted as saying by 'The Mirror'.
Although her due date has not officially been confirmed, the Duchess of Cambridge told well-wishers at a charity event last month that "I'm due mid-April, to the end of April."
Quoting palace sources, the report said the actual date of delivery was April 25.
Parking restrictions have already been put in place outside the Lindo Wing of St Mary's Hospital in Paddington, west London, in anticipation of the birth, although the restrictions will only be in place until April 30, suggesting doctors expect the baby to have arrived before then.