More than a fifth of 14-year old girls in the UK report having self-harmed in the previous year.
Source: The Children's Society: The Good Childhood Report 2018
A survey of 11,000 children found 22% of the girls and 9% of the boys said they had hurt themselves on purpose in the year prior to the questionnaire.
Rates of self-harm were worst (46%) among those who were attracted to people of the same or both genders.
The Children's Society report said gender stereotypes and worries about looks were contributing to unhappiness.
Self-harm is when people hurt themselves as a way of dealing with difficult feelings, painful memories or overwhelming situations and experiences. It can include everything from punching or hitting to cutting or burning.