For decades, suicide has been a leading cause of death for teenagers, and the data suggests the problem may be getting worse.

According to the Centers for Disease Control and Prevention, suicide rates are up by 30 percent since 1999 , and new research from Nationwide Children's Hospital shows a disproportionate increase in suicide for girls ages 10 to 14.

According to NBC News, more boys still commit suicide than girls, but the gap is narrowing. The rate of male teen suicide also increased, but by a smaller amount .

Donna Ruch, a researcher at Nationwide Children's Hospital in Columbus, OH and the study's author, says that doctors still don't know what is driving the increase in suicide. It could be partly due to better data collection and reporting simply painting a more accurate picture of suicide in the United States, but experts also believe social media, bullying, mental health issues and popular culture all play at least some part.

"With suicide, it's never just one cause," psychologist Julie Cerel told NBC News. "But at the same time, it's hard to figure out how each of those areas play into the pain teenagers are feeling."

Cerel says parents and other trusted adults need to be able to have open conversations with children about suicide.

"Have frank conversations about suicide and hopelessness and pain," Cerel said. "Be able to ask your kids and your kids' friends: "Are you hopeless? Are you thinking of killing yourself?"

The CDC says that as many as half of victims did not previously have known mental health issues, but researchers believe depression (often undiagnosed) to be a leading cause of suicide. For more information on mental health for children and resources about talking about these issues with your children, you can click here to check out Nationwide's On Our Sleeves Program .

If you or someone you know is at risk of suicide, contact the National Suicide Prevention Lifeline at 800.273.8255 .