The total number of child brides in Africa will rise from 125 million to 310 million by 2050 if current trends persist, making almost half of the world's child brides African, a Unicef report released on Thursday warned.

The report showed that worldwide more than 700 million women and girls were married before their 18th birthday. Among them 17%, (125 million), live in Africa, and more than one in three of these women and girls (over 40 million) entered into marriage before age 15.

Girls in rural areas are twice as likely to become child brides as girls from urban areas, and similarly, girls from the poorest households are twice as likely to marry before age 18 as girls from the richest households, the report found.

According to the report, in all other regions of the world, current rates of reduction and demographic trends mean there will be fewer child brides each year.

However, by 2050 Africa will surpass South Asia as the region with the highest number of women aged 20 to 24 who were married as children.

The report pointed to slow rates of reduction, combined with rapid population growth in Africa as major causes for the projected increase.

Across Africa, the percentage of young women who were married as children has dropped from 44% in 1990 to 34% today, while Africa's total population of girls was expected to rise from 275 million today to 465 million by 2050.

Unicef experts believe when children get married, their prospects for a healthy, successful life decline drastically, often setting off an intergenerational cycle of poverty.

Besides, child brides are less likely to finish school, more likely to be victims of violence and become infected with HIV. Also children born to teenage mothers have a higher risk of being stillborn, dying soon after birth and having low birth weight.