Amanda Serrano retains titles against Danila Ramos in historic contest

Amanda Serrano is the first Puerto Rican undisputed world champion

Amanda Serrano retained her featherweight titles against Danila Ramos by unanimous decision in a historic contest for women's boxing.

It was the first time since 2007 that women have been in the ring for a title fight for as long as their male counterparts, with Serrano coming out on top after 12 three-minute rounds.

Women's bouts are usually contested over 10 two-minute rounds.

Serrano, 35, said after the fight she "really couldn't feel the difference".

"In the sixth round, I was like, is it really three minutes or did they go back to two minutes?" she told ESPN after retaining her WBO, WBA and IBF world featherweight titles.

"I felt good. I was in really good shape. I trained really hard for this fight knowing I had to go out there and prove to everybody, prove people right or prove people wrong, that women can do whatever they put their minds to."

• Should women compete in three-minute rounds?

Her WBC title was not on the line as the Mexico City-based sanctioning body would not endorse extending the length of the rounds in female boxing, citing "health and safety" concerns.

Earlier this year, more than 20 current and former women boxers, including Serrano, signed a statement saying they wanted to be able to fight three-minute rounds.

Brazilian Ramos said she "knew this was the time" to be part of the historic contest, adding: "This was the time for me to come through, come by and to let the world meet me. I've always been a woman who fought for equality and women's rights."

Advocates for three-minute rounds argue more time spent in the ring increases the chance of a knockout and consequently a better spectacle.

However, Serrano and Ramos went the full 36-minute distance, with seven-weight champion Serrano winning all 12 rounds.

In 2007, Layla McCarter defeated Donna Biggers and Melissa Hernandez in a fight that was scheduled as 12 three-minute rounds.