One in 30 young men were married as children, according to the first UN analysis of child marriage rates among boys.

Around 115 million boys and men around the world were married before they turned 18, according to Unicef, which warned the issue is often overlooked.

“When we think about child marriage we often think about girls, and rightly so because girls are most affected,” said Claudia Cappa, senior statistics adviser for Unicef, and one of the report’s authors. “But boys do marry in childhood.”

“It’s a rights violation,” she added. “It creates a burden for boys to take on adult responsibilities and roles when they are still children themselves – like providing for a family.”

The analysis found that countries where child marriage among boys was most prevalent did not necessarily have the highest rates of child marriage among girls. Niger, for instance, where three in four girls are married before they reach 18, had much lower rates of child marriage among boys, said Cappa. “Girls [in Niger] tend to marry older men, that’s why you don’t see child marriage in boys to the same extent,” she said.

The analysis is based on data from household surveys across 82 low and middle income countries, which found that one in 21 young men and boys had been married as children. Once wealthier countries are factored in, the prevalence rate drops to one in 30. The researchers assume the prevalence of child marriage among boys is close to zero in wealthier countries.

While child marriage among girls is most common in sub-Saharan Africa, cases among boys are prevalent in countries across a range of regions.

Central African Republic, where almost a third of boys and men are child grooms, had the highest rate of child marriage among boys, followed by Nicaragua (19%), Madagascar (13%), Nauru (12%) and Honduras (12%), according to research published in the journal Vulnerable Children and Youth Studies.

Girls are disproportionately affected by child marriage: one in five young women aged 20 to 24 were married before they turned 18. A greater proportion of girls are also married before the age of 15, said Cappa, and they are more likely to face health problems related to early pregnancy and childbirth.

The study concluded that, much like girls, boys most at risk of child marriage tend to come from the poorest households, live in rural areas and have little or no education. Researchers concluded that greater work is needed to identify more specific drivers of marriage among boys.

Very little research has studied male child marriage because it is only relatively recently that data has been collected by governments, said Cappa. She added that previous efforts to tackle child marriage have focused on child brides because much larger number of girls are affected.

“Ultimately there is also a cultural element that comes into play,” she said. “It is the same for other topics as well – think about sexual violence, for instance. For a time it was believed men are not affected or the impact was not as significant – this is not true.”

The prevalence of child marriage is decreasing globally, according to Unicef, with the most progress in the past decade seen in south Asia, where a girl’s risk of marrying in childhood has dropped by more than a third, from nearly 50% to 30%.

Most countries around the world have laws that set a minimum age of marriage, usually at 18. However, many countries have exceptions to this rule, for example, in cases where there is parental consent.