Age at first marriage

Age at first marriage

Age at first marriage

Two indicators are most often used to measure age at first marriage: Median age at first marriage and Percent married before age 15 or before age 18.

  1. Median age at first marriage is the median age in years when women (or men) aged 15–49 first married or lived with a consensual partner.

The indicator uses cumulated single-year percent distributions of age at first marriage or first union. Age at first marriage or first union is obtained by subtracting the birth year of the woman (or man) from the year of first marriage or consensual living with partner. Age at first marriage can also be obtained directly through a survey question, for example, “At what age were you first married or started living with a man (or a woman)?”

The indicator is calculated as:

(Number of women [or men] who were married or started living in a consensual union at single year of age categories/Total number of women [or men] aged 15-49 of all marital statuses) X 100

Once the percentages have been calculated within specific age group categories, medians are calculated from the cumulated single year of age percent distributions for the ages women (or men) were first married. The median is linearly interpolated between the age values by which 50 percent or more of the women (or men) were first married or lived in consensual union. (MACRO/DHS, 2011; Croft et al., 2018)

For example, if 10% of women aged 15-49 were married at age 17, 30% at age 18, 41% at age 19 and 62% at age 20, the graph would look like this:

Age at first marriage

In this illustration, the interpolated calculated median by which 50 percent or more of the women surveyed were already married or living with a consensual partner is roughly 19.5, which when rounded up to the next completed year of age, is 20 years of age.

  1. Percent married before age 15 or before age 18 is the percent of women (or men) aged 20-24 who were married or in a union before age 15 or before age 18. It is commonly referred to as “Child marriage” (i.e., any marriage or union where at least one of the parties is under 18 years old) (Girls Not Brides, UNICEF 2022).

The indicator is calculated as:

(Number of women [or men] aged 20-24 who were first married or in union before age 15 [or before age 18]/Total number of women aged 20-24 in the population) x 100.

Ages 15 and 18 are used as the standard across countries; age 18 is considered the common age of majority, though the threshold age between childhood and adulthood varies across countries, as does the legal age at marriage (UNStats, 2022). The indicator can also be calculated using the national minimum legal age of marriage.

Data Requirements:

Survey information on the ages when women (and men) were first married or entered consensual unions and information on the total number of women (and men) ages 15–49 surveyed. Data can be disaggregated by relevant socioeconomic and demographic factors, such as education, wealth quintile, and urban/rural location.

Population-based surveys such as the Demographic Health Survey (DHS), Multiple Indicator Cluster Survey (MICS), PMA2020, or Reproductive Health Survey.

This indicator can provide information on the current status and trends over time on the ages at which young women (or men) enter marriage and consensual unions. The proportion of women (or men) aged 20-24 years who were married or in a union before age 15 and before age 18 is a Sustainable Development Goals (SDG) Indicator for monitoring progress toward ending child, early, and forced marriage (SDG Indicator 5.3.1).

Most research on the consequences of early and forced marriage focuses on girls. Social expectations and economic challenges may pressure girls to marry and bear children at early ages before they are emotionally and physically ready. Adolescent girls who are married often find it difficult to access reproductive health services and negotiate the use of family planning methods with their partners. About 21 million women and girls ages 15–19 (both married and unmarried) in developing countries become pregnant each year and approximately 12 million of them give birth (WHO, 2020). For this age group, complications of pregnancy and childbirth are a leading cause of death, with unsafe abortion being a major contributor to maternal mortality, morbidity, and lasting health problems (WHO, 2020). Adolescent mothers are more likely to have inadequate nutrition, anemia, and children with low birth weight. Moreover, early childbearing is linked to obstetric fistula, a devastating and socially isolating condition that can leave women incontinent, disabled, and in chronic pain. An analysis of DHS data from ten countries and related research also shows that early marriage is associated with gender-based violence (Hindin et al., 2008). Early marriage can isolate girls from family and friends and exclude them from participating in their communities, particularly if the girl is below the legal age of marriage, which takes a heavy toll on the girl’s physical and psychological well-being (UNICEF, 2022).

Living in union outside of formal marriage can result in similar consequences as early marriage, though the assumption is often that the partners are considered “adults” even if one or both has not reached the age of 18 (UNICEF, 2022). Without the social recognition of a legal or religious marriage, children in union may suffer additional vulnerabilities (UNICEF, 2022).

Studies show that higher median age at first marriage directly correlates with higher rates of girls in school (UNICEF, 2005). Helping girls go to and stay in school may be one of the best ways to foster a later and chosen marriage.

The median is based on all women, including those who have never been married or lived in a consensual union. If disaggregating by age groups (e.g., 15–19; 20–24 years), there may not be a median for younger cohorts of women (since fewer than 50 percent of the cohort may have been married or lived in a consensual union). More helpful indicators for tracking age of marriage trends for the younger age groups may be the percentage married before age 15 for those ages 15–19 years and the percentage married before age 18 for those ages 20–24 years.

Survey questions directly asking age at first marriage or first union may be subject to response bias, especially in contexts where there could be social or legal sanctions to underage marriage. One way to limit the bias is to calculate age at first marriage by indirectly collecting the information through date (year) of birth and date (year) of first marriage or union.

The measures of child marriage are retrospective by design and capture age at first marriage among populations that have completed the risk period. Assessment of marriage among persons still within an age group (under 18 years old, for example) are possible, but would result in underestimates, as persons who are not currently married may still do so before they transition into the older age group (i.e., turn age 18) (UNStats, 2022).

women’s status, empowerment

While most countries declare the minimum age for marriage as 18 and the practice of child marriage has decreased globally over the last 30 years, it remains common in some countries and in others can be found in rural areas and very low-income areas (UNFPA, 2011). Even with a shift towards later marriage in many parts of the world, globally, 19 percent of girls are formally married or in an informal union before their 18th birthday with that number nearly doubling in the least developed countries (UNFPA, 2022). Poverty is one of many factors that places a child at risk of marriage. In turn, child marriage itself is a risk factor for poverty. Thus, one intervention for breaking the cycle of poverty and ultimately improving the health outcomes in a population is to delay age at first marriage. Delaying age at first marriage generally translates into increased schooling and employment opportunities for girls, delayed childbearing, and better outcomes for the girls’ future children (UNFPA, 2022).

Gender Considerations:

In February 2022, members of the Child, Early & Forced Marriage and Unions and Sexuality Working Group convened to share their perspectives on this indicator and why it can be a limiting—and potentially problematic—marker of success. A webinar brief from their meeting outlines their concerns as follows:

  • Analyzing age at marriage as the axis focuses our attention on delaying marriages as an intervention, and obscures the root cause of early marriage, which is gender inequality. The patriarchal social norms and structures that limit girls’ abilities to make choices about their sexuality, bodies, and relationships don’t disappear when a girl turns 18. Girls who get married at 19 often still lack control over who they marry, whether or when they have children, or if they can pursue careers.
  • The age at which girls marry only tells part of the story, and not always the most important part. Initiatives that do not address social norms and the barriers to girls’ life opportunities may succeed in increasing girls’ age of marriage and thus be considered successful, without solving the real problem.
  • Efforts directed at the age of marriage tend to involve legal responses that center on punishing men and boys rather than supporting the needs and wants of girls. Girls are often unable to access the legal system to their benefit and the age of marriage laws may cause harm by driving behaviors underground or by penalizing girls who choose marriage of their own volition.
  • A focus on the age of marriage can render invisible the needs and realities of underage girls already married or in unions. These girls could benefit from many of the same interventions as unmarried girls.

Thus, age of marriage may still be one measure to assess child marriage interventions, but it cannot be the only or most important indicator. Other measures of success may relate to gender-equitable attitudes, girls’ participation in public spaces, and participation in marital decision-making, for example. Moreover, donors should not misinterpret the value of supporting types of interventions solely based on whether girls marry before or after 18 without looking at child marriage as a symptom or manifestation of the underlying problems of gender inequality, violence against girls and women, harmful gender norms, and poverty (Child, Early & Forced Marriage and Unions and Sexuality Working Group, 2022).

Child, Early & Forced Marriage and Unions and Sexuality Working Group. (2022). Webinar Brief: What counts as success in child marriage interventions? A discussion on age, agency and measuring change that matters.

Croft TN, Marshall AMJ, Allen CK, et al. (2018). Guide to DHS Statistics. Rockville, MD, USA: ICF.

Girls Not Brides. Accessed July 19, 2022.

Hindin M, Kishor S, Asara D. (2008). Intimate Partner Violence among Couples in 10 DHS Countries: Predictors and Health Outcomes. DHS Analytical Studies No. 18. Calverton, MD: Macro International.

MACRO International. (2011). DHS Statistics, Age at First Marriage, Calverton, MD: MACRO, Int’l.

U.N. Development Program. (2007). Tracking the Millennium Development Goals, MDG Monitor, New York: UNDP.

UNFPA. (2011). Child Marriage Fact Sheet, New York: UNFPA.

UNFPA. (2022). Child Marriage.

UNICEF. Child Marriage. Accessed July 19, 2022.

UNICEF. (2005). Early Marriage: A Harmful Traditional Practice. New York: United Nations.

United Nations Department of Economic and Social Affairs: Statistics Division (UNStats). (2022). SDG Indicators: Metadata Repository.

WHO. (2020). Adolescent Pregnancy: Key Facts.,million%20of%20them%20give%20birth.

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