WBO welterweight champion Jeff Horn and his wife Jo have welcomed their first child, capping off a fairytale 2017 for the couple.

Isabelle Kate Horn was born at 7:40pm on Saturday, weighing in at 3.58kg or 7.15 pounds, and both mum and daughter are doing well.

The couple said the arrival topped off a wonderful year, including Horn capturing the World Boxing Organization welterweight title by winning a twelve round unanimous decision, in a huge upset, over eight division world champion Manny Pacquiao in July at the Suncorp Stadium in Brisbane, Australia - with 51,000 fans in attendance.

"Winning a world title was a tremendous achievement but Isabelle's arrival is the greatest gift of all and has officially confirmed 2017 as the best year of our lives," the couple said in a statement.

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Isabelle's arrival comes less than three weeks after Horn defended his crown against English fighter Gary Corcoran, with Jo, then 38-weeks pregnant, watching the bout ringside.

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There were concerns the excitement of the bout might have been enough to bring on the labour, prompting the couple to have an obstetrician on site, and an ambulance on stand-by in case the baby came early.

Horn came through with an eleven round stoppage victory.

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Now the 2012 Australian Olympian is being lined up to fight mandatory challenger Terence Crawford, who unified the entire junior welterweight division and now moves to welterweight.

Top Rank's CEO Bob Arum, who promotes Crawford and has a fight option on Horn, wants to stage the fight on April 21 at the T-Mobile Arena in Las Vegas.

But there is another carrot hanging over Horn's head, with a lucrative $2 million domestic showdown against former world champion Anthony Mundine.

The situation with Horn's next fight should be sorted out in the coming weeks.