A 22-year-old beauty queen has been stripped of her crown after revealing she's pregnant.

Joyce Prado, who won Miss Bolivia Universe last year, has lost her title over a "breach of contract".

The pageant queen has been with her Paraguayan model boyfriend Rodrigo Giménez for four months, but it is against Miss Universe rules for winners to get pregnant or tie the knot while holding the title.

Ms Prado's modelling agency, Promociones Gloria, revealed on their Facebook page on Friday that her two crowns had been removed for "reasons that are strictly related to contractual breach".

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However the details around her sudden departure from her role wasn't revealed for "confidentiality reasons".

Now, Ms Prado has taken to Instagram to reveal her pregnancy, sharing a happy photo of her and Mr Giménez lovingly holding a tiny baby romper.

"Becoming a father or mother can be the most important challenge that we present in life, but while it may be difficult, it can also become the most rewarding thing in the world," Ms Prado wrote in the post.

"I want to share with you that I am the happiest woman in the world because my life is full of love, because next to the man of my dreams we are starting to live the most beautiful stage of our lives."

But while Ms Prado appeared unfazed by the fact she had lost her crown, looking ahead to life as a mum, fans were not happy with the "stupid" rules.

According to Miss Universe guidelines, "contestants may not be married or pregnant." They also cannot have previously been married or parented a child. As for titleholders, they are "required to remain unmarried throughout their reign."

The contest began in 1952, but in recent years it has been embroiled in controversy over its outdated rules and objectification of women.