But in a small number of countries, adulthood, or the “age of majority” may be reached before age 18. (The CRC makes an exception for national laws recognizing an earlier age of majority.) Some countries and cultures consider adulthood a state achieved upon marriage – for example, countries where full age means the age of 18 years and above, and any married woman is deemed to be of full age, even if she is under 18. And other countries have an older minimum age of marriage, such as Nepal, where the law requires both men and women be at least 20 when they marry.

The concept of marriage also varies – it can be formal or informal, governed by civil law, common law or religious law, or simply be a customary practice. In many parts of the world, for example, marriages may be recognized by the community without legal registration, marked simply with a ceremony. In countries where polygamous marriage is not permitted by civil law, second and third marriages often take place without formal registration.

Major surveys try to account for this variation when measuring child marriage. Multiple Indicators Cluster Surveys and Demographic and Health Surveys, for example, collect information on the date and age at which women and men were married or first started living with their first spouses or partners.

Regardless of these varying definitions, child marriage is a serious human rights violation that directly threatens lives, health, safety and education of girls and boys, limiting their future prospects.

It can be hard to imagine why someone would choose to have their child married off. But for millions of people, child marriage can seem like the best – or only – option.

Daughters are frequently seen as burdens or commodities because of pervasive gender inequality. Impoverished parents often believe marriage will secure a daughter’s future by making a husband or his family responsible for her care. This may be the case when parents face economic hardships or when girls are forced by poverty or circumstance to drop out of school. In places where the bride’s family pays a dowry to the groom’s family, younger brides typically command smaller dowries, creating an incentive for parents to marry their daughters off early. In places where the groom’s family pays a bride price, parents in difficult circumstances may marry off their daughters as a source of income.

Parents – especially in humanitarian crises – often view marriage as a way to protect their daughters from sexual violence. Child marriage rates have been known to increase during the chaos of war, as families endure both economic instability and fear of violence. Yet child marriage itself leads to girls experiencing high levels of sexual, physical and emotional violence from their intimate partners.

Although most adolescent pregnancies in the developing world take place among girls who are already married, in some places, teenage pregnancy – or even the possibility of teenage pregnancy – prompts parents to marry off their daughters. This is seen in both wealthy and poor countries where communities consider pregnancy outside of marriage to be shameful. Girls may even be forced to marry rapists to spare their families the stigma associated with unmarried pregnancy.

And not all child marriages are the result of parents’ or guardians’ decisions. Often, adolescents themselves decide to marry or enter an informal union living with their partner, whether a peer or an older individual. These marriages may be a way to exercise independence, leave home or escape difficult circumstances, including desperate poverty or family violence. Restrictions on adolescent sexuality outside of marriage also drive some adolescents to see marriage as the only way to be sexually active.

In most cases, child marriage is the result of girls and families having few choices. Overwhelmingly, when young people have a choice, they marry later.

Child marriage is actually very common.

More than 650 million women and girls alive today were married before their 18th birthday. Nineteen per cent of women between the ages of 20 and 24 around the world were child brides. And while child marriage is most prevalent in low- and middle-income countries, it also takes place in high-income countries.

There is good news: global child marriage rates are slowly falling. Around 2000, one in three women between the ages of 20 and 24 reported they had been married as children. In 2021, this number was just under one in five. Rates of child marriage before age 15 also fell, from 11 per cent in 2000 to 5 per cent in 2021.

Still, progress has been uneven and child marriage is not declining fast enough. Because of population growth in regions where child marriage is more prevalent such as West and Central Africa, the rate of decline is slow and the total number of child marriages is projected to increase by 2030. COVID-19 has also set back efforts and exacerbated pressures on families thus leading to projected increases in child marriage. To change this, we must accelerate our actions to end the practice. 

South Asia has seen dramatic declines in child marriage over the last decade, and now the global burden of child marriage is shifting to sub-Saharan Africa. Of the most recently married child brides, close to one in three are now in sub-Saharan Africa, compared to one in five a decade ago. While sub-Saharan Africa still has some of the highest rates of child marriage, South Asia is home to the largest numbers of child brides.

Child marriage takes place all over the world.

It even happens in developed countries – including the United States and United Kingdom. Many people assume that when child marriage takes place in affluent countries, it only involves immigrant communities. This is not the case. Child marriage is known to take place across a wide range of communities, ethnicities and religions.

Still, child marriage is much more common in the developing world because one of the main driving factors is poverty.

The highest rates of child marriage are seen in West and Central Africa, where over four in ten girls were married before age 18. In terms of sheer numbers, South Asia is home to the largest numbers of child brides.

Children can be married off at any age. The most common ages at which children are married are 16 and 17.

Marriages that take place before age 15 are considered “very early marriages.” These marriages have a particularly negative impact on girls, interrupting their education earlier and jeopardizing their health more acutely. Research by UNFPA shows that child marriage rates increase gradually until age 14 and accelerate significantly thereafter at ages 15 through 17. The majority of child marriage thus occurs in middle adolescence. 

In circumstances where parents are under enormous pressure to marry off their daughters – for those living in extreme poverty or in conflict settings, for instance – marriages have been reported among girls around 11 or 12 because girls are seen both as being ready for marriage and at risk of sexual violence.

In some cases, children are as young as five when they are married, although this is rare. Extremely young brides and grooms are sometimes married in ceremony only but live with their parents until they reach adolescence.

Children who are married – and they are overwhelmingly girls – tend to have spouses who are much older. When this is the case, the girls are generally more vulnerable and less able to advocate for their needs and desires.

Demographic and Health Surveys (tools for collecting key health and demographic information) even track age differences between girls and their spouses. This information is used as one of a variety of factors to evaluate the well-being of girls in a community.

Still, child marriages are not always unions between girls and much-older men. In some communities, it is customary to wed girls and boys of similar ages. And there are also cases of adolescents marrying one another voluntarily – sometimes called “love marriages” – and entering cohabiting unions forbidden by family members. Such marriages can put young people at risk of retributive violence, and because the spouses often run away, they may lack economic support or face social isolation. 

While the vast majority of child marriages involve girls, boys can also be married off.

However, UNFPA has found that in all 82 low- and middle-income countries for which there are data, the prevalence of child marriage is significantly lower for males than females. Only 1 in 25 boys (3.8 per cent) marry before they reach age 18, while marriage before age 15 is practically non-existent in boys (0.3 per cent). Only 10 countries have a child marriage prevalence for boys over 10 per cent – including 16 per cent in Madagascar; 14 per cent in Pakistan; 13 per cent in Central African Republic and the Lao People's Democratic Republic; 12 per cent in Comoros, Honduras, the Marshall Islands and Nauru; 11 per cent in Nepal; and 10 per cent in Guatemala.  

Child marriage rates for boys are very low even in countries where child marriage among girls is relatively high. 

Child marriage undermines children’s human rights and derails their lives and future opportunities.

At the most basic level, it denies children the right to choose – with full and free consent and without coercion or fear – whom to marry and when. This is one of life’s most important decisions.

And there are additional consequences. Child brides are more likely to become pregnant before their bodies are mature, increasing the risks of both maternal and newborn death and morbidity. In developing countries, the majority of births to adolescent girls occur within a marriage or a union. In these countries, where access to sexual and reproductive health services is generally low, complications from pregnancy and childbirth can be deadly. In fact, globally, these complications are the leading cause of death among adolescent girls.

Children who are married off are also vulnerable to sexually transmitted infections (STIs), including HIV. Contributing to this problem is the fact that girls who have dropped out of school are more vulnerable to child marriage and less likely to be equipped with information about protecting themselves from STIs and unplanned pregnancy.

Child brides are particularly vulnerable to violence and abuse. Young women married as children were 1.5 times more likely to experience physical and/or sexual intimate partner violence than young women married as adults. They are less able to advocate for themselves and less able to escape abusive relationships. Mental illness is common among child brides, for example, due to their experience of violence. Girls who marry young are also more likely to think that wife beating is justified than women who marry later in life. 

Married girls rarely enrol in school because they are expected to assume significant domestic responsibilities. This limits their future potential and makes it harder for their families to escape poverty.

Lack of education and empowerment also mean girls are less able to advocate for the well-being of their own children. The children of child brides have higher mortality rates, worse nutritional outcomes and tend to be less educated.

Girls in informal unions living with their partners experience many of the same consequences.

Cumulatively, child marriage takes an enormous toll on communities, workforces and economies, and the loss is carried over generations.

Child marriage is almost universally banned.

Two of the most broadly endorsed human rights agreements in the world, the Convention on the Rights of the Child (CRC) and the Convention on the Elimination of All Forms of Discrimination against Women (CEDAW), address child marriage. The CRC establishes the internationally agreed definition of a child, and the right of children to health, education, protection from violence and protection from sexual exploitation and abuse, all of which are violated by child marriage. The CEDAW states unequivocally: “The betrothal and the marriage of a child shall have no legal effect, and all necessary action, including legislation, shall be taken to specify a minimum age for marriage and to make the registration of marriages in an official registry compulsory.” Together, these treaties have been signed or ratified by every country except one.

Still, there are some national laws that enable different interpretations of this agreed principle. Many countries permit exceptions with parental consent or under religious or customary law.

Even in places where child marriage is clearly legally prohibited, enforcement can be complicated by the fact that many child marriages – and many marriages in general – are not legally registered.

There are no major religious traditions that require child marriage. Yet child marriage persists, across many cultures and religions. Child marriage does not warrant protection as a cultural or religious practice – governments around the world have overwhelmingly, and independently, decided that child marriage is a grave violation of human rights.

In places where child marriage persists, evidence about its harms are usually convincing to policymakers, community leaders, religious leaders and parents. In fact, there are many examples of cultural and religious leaders taking a strong stance against child marriage. But prohibitions themselves are not always sufficient, because child marriage is typically the result of a lack of choices and because it is viewed as the norm. Families, girls, and communities  need alternatives to child marriage that can take the form of education and employment opportunities, social protection from income loss and catastrophic expenditures and safer, more stable living environments.

Laws prohibiting child marriage need to be enacted, strengthened and enforced. And more attention is needed to related laws such as on bride price and dowry, marital rape, birth and marriage registration and mandatory schooling.

But laws alone will not end child marriage.

Fundamentally, gender equality must be advanced. When educating daughters is considered as worthwhile as educating sons, when communities – both men and women – give equal weight to the future potential of girls and boys, there is less motivation to engage in child marriage.

Adolescent girls and boys are less likely to want to marry before age 18 when they are empowered with information about their sexual and reproductive health and when they are able to decide freely and responsibly matters related to their sexuality, free of coercion, discrimination and violence.

Improved circumstances for families can also reduce the incentive to marry off children. Families, including girls, need to be able to live in peace and move in safety. And poverty and economic inequality, which drive so many child marriages, must be eradicated. For this, many changes are needed, including social safety nets for girls and their families, as well as improved access to quality education, health services and economic opportunities.

Girls can play an important role in ending child marriage – when they know their rights and have access to the right information and opportunities. UNFPA has seen that when girls are empowered to claim their rights, they can persuade their families to delay or cancel engagements. Instead, they can stay in school, gain skills and support their families economically. Many have been inspired to become advocates and leaders in their communities.

Ending child marriage in these countries by 2030, researchers concluded, is surprisingly affordable: it would cost just $35 billion.

In other words, it costs roughly $600 to spare each child bride.

The $35 billion investment – in educational interventions, empowerment initiatives, and programmes that change social norms around child marriage – would avert approximately 58 million child marriages. On top of that, girls who escape early marriage will be able to “make a more productive contribution to the household enterprise,” yielding significant benefits to their communities over time. 

People occasionally refer to the term “child, early and forced marriage.” This creates the impression that these terms are distinct. In fact, they are overlapping.

Child marriage and early marriage largely refer to the same thing: marriages in which one or both spouses are under 18 years old. However, early marriage is also sometimes used to describe marriages in which one or both spouses are 18 or older, but with a compromised ability to grant consent. For example, the marriage of a 19-year-old who is not physically or emotionally mature, or who does not have sufficient information about her choices, would be considered an early marriage.

Forced marriage is a marriage in which one or both spouses do not give full and free consent, regardless of age. Forced marriage can also refer to a union in which one or both spouses are unable to end or leave the marriage.

Because in most countries children are not considered able to give legal consent, all child marriages are sometimes considered forced marriages. However, there are many instances of two adolescents under the age of 18 marrying each other voluntarily, called “love marriages” in some contexts.