It's a global scandal that 50,000 teenagers die each year due to pregnancy and childbirth complications, says British charity Save the Children.
The world should renew its focus on family planning, the charity claimed ahead of a summit set to take place in London next month highlighting UN figures showing pregnancy and childbirth as leading causes of death for adolescent girls.
In a report entitled, How Family Planning Saves Children's Lives, Save the Children also cited official data which reveals that nearly one million babies born to teenage mothers die each year before their first birthday.
"The issue of children having children - and dying because their bodies are too immature to deliver the baby - is a global scandal," said Save the Children's Chief Executive, Justin Forsyth.
"This is a tragedy not just for those girls but also for their children: babies are 60 per cent more likely to die if their mother is under 18.
"In the developing world, family planning isn't just a lifestyle choice. Children's lives depend on it," Forsyth concluded.
Childbirth is the leading killer of adolescent girls in Africa, according to UN figures.
Worldwide, one in five girls give birth before they turn 18, according to the report.
It also highlighted figures which showed that the risk of a 15-year-old ultimately dying in pregnancy or childbirth was five times higher for a girl under the age of 15 than for a woman in her twenties.
The charity called for equal access to family planning for all women; for women's rights to be guaranteed and enshrined in law; and for investment in education and health workers.
If that were achieved, the report claims that 30 per cent of maternal deaths and 20 per cent of neo-natal deaths in the developing world could be prevented.
World leaders will gather in London on July 11 for a family planning summit hosted by the British Government and the Bill & Melinda Gates Foundation.