Harper keeps her WBA crown and was unable to defeat the skilled Braekhus for the vacant WBO crown. Harper(14-1-2) won the fight with a score of 97-93 from one judge, but the other two scored it 95-95.
Eddie Hearn, Harper's promoter, called the outcome "a joke".
"It was my own fault for letting it get that close," said Harper in media reports.
"I should have stepped up the gears. I felt the extra weight of Cecilia(37-2-1). Thanks to Cecilia for a great fight," said Harper in media reports.
In the opening rounds, there was nothing between the fighters; Braekhus was more eager than her opponent to step forward and throw a jab.
The former undisputed welterweight champion arrived at the venue with a low-key ring walk and was all business as she sought to make up for missing the first scheduled fight with Harper because of illness.
In the sixth round, Harper took control by landing a few body blows on a fatigued Braekhus who was having trouble moving from the middle of the ring.
Harper gained more control thanks to a ferocious left hook in round seven and a terrifying combination in round nine, but Braekhus countered with some solid uppercuts of her own and finished the fight well, which might have been enough to earn her a draw.
Harper weighed in at 10st 10lb, 4 lb. under the limit and 3 lb. lighter than Braekhus. Harper had risen up three weight divisions to defeat Hannah Rankin and win the title of two-weight champion in September 2022.
"Getting in the ring with these bigger girls, you feel it," said Harper in media reports.
"I love being back here in Sheffield, gutted I didn't get the win for you guys. Thanks for buying the tickets and hopefully next time I can get a win for you," said Harper in media reports.
(Additional reporting provided by Joseph Hammond)
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