Around the world an estimated 3,500 girls under the age of 15 become child brides every day, while another 21,000 get married before reaching the age of 18.
The consequences of such early marriages, according to a new report by the Christian humanitarian organisation, World Vision, include an increased risk of HIV and maternal death, an abrupt end to a girl's education and a greater chance of violence and abuse.
The practise of coercing girls into early marriage occurs all over the world, but the report, "Before She's Ready", lists 15 countries where it is most prevalent.
In Bangladesh, which ranks number one, more than half of all girls (52.5 percent) are married before they turn 16; in Niger the proportion is 37.6 percent, and 34.9 percent in Chad. Other countries included in the top 15 are Ethiopia, India, Nigeria and Mozambique.
The report combines the observations of World Vision staff working in many of these countries with previous research on the issue, and identifies poverty as one of the main factors driving early marriage.
In communities hit by natural disasters or conflict, where families traditionally receive a "bride price" when daughters marry, early marriage can be a desperate bid to raise money to feed the rest of the family. Recent sharp increases in food prices have seen the practice become more common in places such as rural Afghanistan.
Growing numbers of girls orphaned as a result of HIV/AIDS are also being pushed into early marriages by extended family members no longer willing or able to care for them.
Orphanhood is also a significant risk factor for sexual abuse resulting from forced early marriage. The report tells the story of Jane from Ghana, who was orphaned at the age of five and taken in by her aunt. At the age of 13, she was "given" to her aunt's husband as a second wife. She bore him two children before running away.
|Resisting sexual intercourse isn't an option in most early marriages, where consummation is considered the male's right|
Culture and religion also play a role. In some cases, parents believe marrying off their daughters at a young age will protect them from the dishonour of becoming pregnant or sexually active outside of wedlock.
Catherine Demba, World Vision's national child protection coordinator, observed that in some parts of Chad it is considered a curse for a girl to begin menstruating while still living under her parents' roof.
"Resisting sexual intercourse isn't an option in most early marriages, where consummation is considered the male's right," notes the report. Forced sex can cause tissue damage, making girls more susceptible to contracting sexually transmitted infections from husbands who may have other partners or wives.
Research cited in the report from both Kenya and Zambia found higher rates of HIV infection among married adolescent girls than among their unmarried, sexually active counterparts.
Pregnancy and childbirth also carry much greater risks for pre-teen and teenage mothers. Pregnancy-related deaths are the leading cause of mortality among girls aged 15 to 19 worldwide, and complications such as fistula - a tearing of the tissue that separates the bladder or bowel from the vagina - are more common when girls give birth when they are too young.
Studies show that women married as children are also significantly more likely to experience domestic violence and abuse. A survey in India found that girls who married before the age of 18 were twice as likely to report being beaten by their husbands than girls who married later, and three times more likely to have been forced to have sex in the previous six months.
Besides the health risks, early marriage usually means that girls are denied the opportunity to continue their education, which in turn limits their future ability to support themselves and their children. Lower education levels have also been associated with higher risks of HIV infection.
The report points out that laws prohibiting child marriage exist in most countries but have done little to stop the practise, especially where it is linked to the genuine economic needs of struggling families.
Addressing these needs may be the best way to delay marriage and childbearing. World Vision recommends job training, microfinance schemes and agricultural input programmes to remove the necessity of offering a daughter for marriage.