A friend of the Duke and Duchess of Cambridge told the Mail Online on Sunday that Middleton's official due date is July 13. If that is true, the royal baby would arrive in the middle of the four-day festival, scheduled July 11-14. The event celebrates 60 years of the queen's reign.
The Clarence House Press Office told ABC News they could not comment on the report but said "the baby is expected to be born in July."
There was earlier speculation that the baby could share a July 1 birthday with Princess Diana. Bookies even placed their bets after Middleton's pregnancy was announced in December.
ABC News contributed to this report.