Starting next year, Miss Singapore Universe contestants could be born a man as pageant organisers have changed the rules.

Women who have undergone sex change may now apply and compete against natural-born women, confirmed local organiser on Sunday.

This is considered a major change in the rule books for the contest - which will be its 13th edition in 2013 - as it will see natural-born females compete against transgender contestants for the crown.

Traditionally, only natural-born women aged between 18 to 27, are allowed entry to the contest for both nationals and international editions. The pageant is co-owned by United States real estate mogul Donald Trump and television network NBC.

Local organiser, Derrol Stepenny Promotions, said they will abide by the new rules, but they are still waiting for specific instructions about the change from the competition's parent organisation, reported The Straits Times.

Earlier in April, the Singapore organiser said they were considering accepting contestants who have had a sex change. Yesterday, while unveiling this year's finalists, organisers confirmed the move.

The new rule comes after a Canadian transgender woman, Jenna Talackova (pictured above), was disqualified from her country's competition. She was eventually allowed to return, after hinting that she would file a discrimination lawsuit against the organisers.

While it is too early to tell if the move is a good or bad one, Derrol Stepenny Promotions managing director and organising chairman Errol Pang urged sponsors to continue to support.

A spokesman for the company also said that the change means that natural-born hopefuls will have to work harder to vie for the title.

"They will be competing against transgender women who have had plastic surgery," she said.

"It will be up to them to compete in other ways besides through their natural beauty, for example through their wit and intelligence."

When it comes to plastic surgery, natural-born women who have gone through extensive surgery may also have an unfair advantage over others. But it seems, there is no issue at the moment as it does not affect the overall outcome, reported The New Paper.

"We don't have a process of checking whether a participant has gone through plastic surgery, and it is not a question that we normally ask the girls. It is not an issue and doesn't affect the outcome at all," said Ms Penelope Pang, the managing director of Warner Artistes, one of the supporting companies of Miss Universe Singapore.

Previously, Miss Universe has permitted plastic surgery for its contestants, and they are not required to disclose any work that they have done. Mr Trump told US broadcaster ABC in 2001 that "there's nothing we can do about it" and "there's no policing it."

Several Miss Universe contestants have admitted undergoing some sort of plastic surgery in the past. Miss Argentina 2011 Natalia Rodriguez reportedly admitted at a Miss Universe press conference that she had a breast implant years before she had planned to compete in a beauty pageant.

Miss Brazil 2001 Juliana Borges has openly admitted to have undergone 19 procedures before the competition. She told ABC that just like how students study to do well for an exam, she works on her figure to have the perfect body. Ms Borges did not make it to the top 10.

Specifics on how the new rule will be executed have not yet been announced, and it remains unclear if there will be many transgenders signing up for next year's contests, but for now, this year's Miss Singapore Universe pageant could be the last in which all contestants are natural-born women.

Singapore's 14 beauties will vie for the crown on Sept 9, with the winner representing the republic at the international Miss Universe pageant in December.