According to ministers, the royal baby due next year to the Duke and Duchess of Cambridge will ultimately accede to the throne regardless of its sex after changes in the rules of Royal succession.
In a break with more than 300 years of English constitutional tradition, laws that would have passed the Crown to the oldest male heir will not apply, the Telegraph reported.
Under the previous rules of primogeniture, any male child would have taken precedence in the order of succession over his sisters.
That would have meant that were next year's child to be female, her place in the line of succession could have been taken by any younger brothers.
The laws required to change the succession rules have not yet been passed, but ministers insist that a political agreement David Cameron made with other Commonwealth leaders last year is enough.
At a Commonwealth summit in Perth, Australia, the Prime Minister last year agreed in principle that succession rules will be changed across the Queen's Realms, the 16 nations where the Queen is head of state.
In Perth, a Realms "working group" was established under the leadership of New Zealand to make sure the necessary legislation is acceptable to all countries and that the process is co-ordinated.
However, none of the other Realms have yet formally changed their laws.
Nonetheless, British ministers have insisted that the agreement made in Perth is enough to ensure that the expected child will not be affected by primogeniture rules.
Nick Clegg, the Deputy Prime Minister, last month told MPs that there has been a "de facto" change in the succession rules.
"The change to the rule of male primogeniture came into effect from the point of the Perth conference last year, so even if we had not secured all the necessary legislative changes in all the realms, we would none the less be able to proceed on the basis that the outdated rule of male primogeniture no longer prevails," he said.
"A de facto change has already been introduced pending the legal changes that now need to be made," he added.