An estimated one in three girls in the developing world is married before the age of 18, with one girl married off every two seconds, according to experts.
The World Bank said ending child marriage would reduce population growth, boost girls’ educational achievements and increase their earnings.
It would also lead to women having healthier and better educated children, further boosting prosperity.
“Child marriage not only puts a stop to girls’ hopes and dreams, it also hampers efforts to end poverty and achieve economic growth and equity,” World Bank economist Quentin Wodon said in a statement.
“Ending this practice is not only the morally right thing to do but also the economically smart thing to do,” added Wodon, who co-authored the report – the first to look at the economic impact of child marriage.
One of the biggest economic benefits of ending child marriage would derive from a reduction in population growth, according to the study co-authored by the International Centre for Research on Women.
Girls who marry young have more children on average than those who delay marriage.
Ending child marriage would reduce fertility rates by 11 per cent on average in 15 of the worst affected countries analyzed in the study.
Global gains from lower population growth could exceed 500 billion dollar annually by 2030, with cumulative gains topping four trillion dollars, the study said.
Although world leaders have pledged to end child marriage by 2030 under the UN Sustainable Development Goals agreed in 2015, investments to end the practice remain limited.
The authors said this was likely partly due to the fact child marriage was seen as a social issue and the economic case had not been made forcefully enough.