One in four U.S. teenage girls killed in a homicide is slain by her dating partner, research showed on Monday, exposing details about the "taboo" issue of dating violence among young people.

Teen and adolescent girls are often embarrassed or reluctant to talk about violence, while some schools and parents resist teaching about violent relationships, experts said.

Nine out of 10 teens and adolescents killed by a dating partner are girls, and nine out of 10 of the killers are boys and men, said researchers at the University of Washington. Their report was published in the JAMA Pediatrics medical journal.

"When they are experiencing things they recognize as unhealthy, they're not likely to disclose to adults in their lives," said lead author Avanti Adhia, a senior fellow at the university's medical school.

"By the time kids get to college, it's too late to start teaching about this," she told the Thomson Reuters Foundation.

The research studied more than 2,000 U.S. homicides of children ages 11 to 18.

It found one-quarter of slain girls were killed by an intimate partner.

A previous study in 2017 by the National Institute of Justice, a U.S. government research agency, found more than two thirds of teens said they had been in a violent intimate relationship in the previous year.

"There's something so taboo about the topic," said Bersheva Delgado, a community liaison at The Healing Center, a New York non-profit group that works with abuse survivors.

While some U.S. states allow minors to file legal orders of protection designed to keep abusers away, others require an adult to be present or parental notification that can deter teens from reporting violence, Adhia said.

Most of the female victims were 17 or 18 and their partners typically four years older, the research found.

About two-thirds of the deaths involved guns.

More than one in four deaths were fueled by jealousy, a break-up or resisting a relationship, Adhia said.