New research from the U.K. finds a sharp increase in the number of adolescent girls reporting self-harm in recent years. The study shows girls are much more likely to harm themselves compared to teenage boys.

Self-harm in children and adolescents is a major public health concern in countries throughout the world and is the strongest risk factor for suicide, which is the second leading cause of death among 15- to 29-year-olds, according to the World Health Organization.

The most common type of self-harm reported was drug overdose, followed by episodes of cutting, self-poisonings, and various other methods of harm including hanging, suffocation, jumping, and scalding.

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To understand the trend among adolescents in the U.K., researchers from the University of Manchester examined data on more than 16,900 patients between the ages of 10 and 19 who had harmed themselves between 2001 and 2014.

Unlike previous research, the study authors looked at cases from general medical practices rather than only those in a hospital setting.

Strikingly, the researchers found that the rate of self-harm in girls aged 13 to 16 rose 68 percent from 2011 to 2014.

They also found that the disturbing behavior was significantly more common in girls — the rate was 37.4 per 10,000 in girls, compared with 12.3 per 10,000 in boys. The study results were published Wednesday in The BMJ.

While the study does not look at the underlying reasons why self-harm rates are higher in teen girls, the study authors say it may have something to do with common mental health issues including depression and anxiety, as well as biological factors such as puberty and onset of sexual activity.

However, study author Navneet Kapur also suggested another possibility: it might be due to an increased willingness among girls to seek help when things become difficult.

Boys might display other behaviors when they are distressed, he explained, including drug and alcohol misuse.

"This applies to females and males across the lifespan," Kapur, the head of research at the Center for Suicide Prevention at the University of Manchester, told CBS News. "The short answer is that we don't know the reason for the apparent rapid increase in self-harm in girls. The rise could reflect better awareness or recording of self-harm in primary care but it could also be a result of increasing stress and higher levels of psychological problems in young people."

The rise of digital media — including social media and its nature of being "always on" — may also play a part.

"Of course such technologies can be helpful and facilitate access to care but there is also a suggestion that extreme 'connectedness' could have detrimental effects," the researchers write.

Kapur notes that while the internet can be a good source of information about how and where to get help, it can also be a place where self-harm is encouraged or normalized and where troubled teens can find information on methods.

Additionally, the study found that teens who self-harmed were nine times more likely to die an unnatural death than their peers, with an especially marked increased risk of suicide and fatal alcohol or drug poisoning.

"This emphasizes the opportunity for earlier intervention in primary care to reduce suicide risk" the authors write.

The researchers note some limitations in the study, including the lack of detail in medical reports of self-harm and the likelihood that not all cases are being identified.

Kapur said he hopes young people and their parents are not "unduly alarmed by these findings."

"We know that for many young people things get better and they no longer hurt themselves as adults," he said. "But of course we must tale self-harm seriously."

Moving forward, Kapur said research should focus on better understanding the reasons for the apparent rise in self-harm, as well as what works for treating young people.

"Talking treatments such as cognitive behavioral therapy help prevent repetition of self-harm in adults," he said. "They also probably work in young people, but the evidence base is much weaker. We need more treatment studies specifically focused on young people."