In a briefing ahead of this week’s Family Planning Summit in London, it said 20,000 adolescent girls gave birth every day, with 95% of these births occurring in developing countries and almost 85% among girls who are married.

The ODI said family planning had attracted less than 20% of the funds spent on HIV, with the latter gaining some $8bn a year from donors while the Family Planning 2020 global partnership received just $1.4bn. 

Researchers said failures to address the issue put both the life chances and lives of millions of girls at risk. 

This was because adolescent girls were more prone to serious medical complications in pregnancy and those who became mothers were less likely to complete school and so to be poor.

Children born to adolescent mothers were also more likely to die in infancy or early childhood.

Progress had happened but had been uneven. Giving examples, the ODI said India had seen “remarkable reductions” in adolescent births, while Brazil had stood still and the situation had worsened over the past decade in Vietnam.

ODI principal research fellow Nicola Jones said: “Donors urgently need to scale up efforts, in a way that we saw with the global campaign against HIV and AIDS, which managed to turn the tide on new infections in less than two decades. 

“If we don’t see a similar mobilisation of funding and strategic interventions then we risk putting the lives and life chances of millions of the world’s girls - and their families - at risk.”

In April, the US government announced it was pulling funding for the United Nations Population Fund (UNFPA), which is focused on family planning and reproductive health.

The Family Planning Summit takes place on 11 July and is co-hosted by the UK’s Department for International Development, UNFPA and the Bill & Melinda Gates Foundation.