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4.1 Under-five mortality rate

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Modified on 2012/03/05 16:06 by MDG Wiki Handbook Categorized as Goal 4
Contents

GOAL AND TARGET ADDRESSED

Goal 4. Reduce child mortality
Target 4.A. Reduce by two-thirds, between 1990 and 2015, the under-five mortality rate

DEFINITION AND METHOD OF COMPUTATION

Definition
The under-five mortality rate (U5MR) is the probability for a child born in a specified year to die before reaching the age of five, if subject to current age-specific mortality rates.

This indicator is expressed as number of deaths per 1,000 live births.

Concepts
A live birth is the complete expulsion or extraction from its mother of a product of conception, irrespective of the duration of the pregnancy, which, after such separation, breathes or shows any other evidence of life, such as beating of the heart, pulsation of the umbilical cord, or definite movement of voluntary muscles, whether or not the umbilical cord has been cut or the placenta is attached. Each product of such a birth is considered a live birth.

Method of computation
The indicator is calculated as equal to the number of deaths of children under five in a calendar year divided by the number of live births in the same year and multiplied by 1,000.

The formula for computing this indicator is as follows:

Image

where U5MR(n) is the under-five mortality rate for the calendar year n; D (0-4, n) is the number of children aged 0 to 4 during year n and who died during year n; and B (n) is the number of live births occurring during year n.

Two methods exist for calculating the U5MR: the direct method and the indirect method. The direct method requires each child’s date of birth, survival status, and date or age at death. This information is typically found in vital registration systems and in household surveys that collect complete birth histories, such as the Demographic and Health Surveys. A complete birth history records the dates of birth, and, if applicable, the dates of death of all children born to each woman that is interviewed. The direct method of estimating child mortality involves taking the data from the complete birth histories and estimating a life table. The method calculates the probability of dying before age five for children born alive during five-year periods before the survey (0-4, 5-9, etc.).

The indirect method requires less detailed information that is available in censuses, general surveys, and household surveys that collect incomplete birth histories such as the Multiple Indicator Cluster Surveys (MICS). This information consists of the total number of children born to each woman, the number who survive and the woman’s age (or the number of years since she first gave birth). The indirect method uses the Brass method, which converts the proportion of reported dead children ever born to women in age groups 15–19, 20–24,… and 45–49 into estimates of the probability of dying before attaining certain ages. The Brass method assumes that the age of the mother can serve as a proxy for the age of her children and thus for how long the children have been exposed to the risk of dying.

Despite requiring minimal data collection efforts, the indirect method involves the use of model life tables to adjust the data for the age pattern of mortality in the general population. Finding an appropriate model life table can be difficult, since the Coale and Demeny model life tables that are usually used are derived largely from the European experience.

RATIONALE AND INTERPRETATION

This indicator is useful because it relates directly to the MDG target of reducing the under-five mortality rate by two-thirds. It also reflects the social, economic and environmental conditions in which children (and others in society) live, including the quality of health care. Data on disease incidence and prevalence (morbidity data) are frequently unavailable, so mortality rates are often used to identify vulnerable populations. This indicator helps identifying such populations because in high-mortality settings a large proportion of all deaths occur before age 5. In fact, the under-five mortality rate captures more than 90 per cent of global mortality among children under the age of 18.

Reducing child mortality is a strongly and universally supported development goal. However, despite considerable progress, a large gap remains in the risks of dying before age 5 between developed and developing countries. For instance, in 2010, under-five mortality was 7 per thousand live births in the developed regions and 63 per thousand in the developing regions. The gap between the developed and developing regions is larger, in proportional terms, for death rates in early childhood than for those in adult ages. Under-five mortality levels are influenced by poverty and low levels of education, particularly of mothers; the availability, accessibility and quality of health services; environmental risks including access to safe water and sanitation; and nutrition.

SOURCES AND DATA COLLECTION

Possible sources of data include vital registration systems, national population censuses, household surveys conducted by global programmes, and multi-purpose surveys conducted without international sponsorship.

The best source of data for computing direct estimates of U5MRs is a complete vital statistics registration system—one covering at least 90 per cent of vital events in the population. However, few developing countries have well-functioning civil registration systems. Alternatively, household surveys that collect complete birth histories (such as the DHS) can be used to get direct estimates of U5MRs.

If no source of direct estimates is available, population censuses, household surveys that collect incomplete birth histories (such as the MICS), and general surveys can be used to derive indirect estimates of U5MRs.

DISAGGREGATION

Under-five mortality generally shows large disparities across geographical areas and between rural and urban areas. Under-five mortality may also vary across socioeconomic groups. Children in some ethnic groups might be at higher risk of malnutrition, poorer health and higher mortality. Gender differences may be more pronounced in some social and ethnic groups and in rural areas.

Under-five mortality can also be disaggregated into separate rates referring, respectively, to the probability of dying before age 1 and the probability of dying between ages 1 and 4.

COMMENTS AND LIMITATIONS

Data on under-five mortality are more complete and timely than data on adult mortality. Under-five mortality rates are also considered to be more robust than infant mortality rates when estimates are based on information drawn from household surveys.

Vital registration systems are the preferred source of data on under-five mortality because data are prospective and cover the entire population. However, in countries lacking a fully functioning vital registration system, household surveys, such as DHS and MICS, have become the primary source of data on child mortality, even though there are some limits to their quality.

Survey data are subject to recall error. Interviewed women may omit births and deaths, or include stillbirths along with live births. Survey data may also suffer from survivor selection bias and age truncation. Mothers may misreport their children’s birth dates, current ages or ages at death—perhaps more so if the child has died. The heaping of deaths at age 12 months is especially common. Age heaping may transfer deaths across the one-year boundary and lead to underestimates of infant mortality rates. Fortunately, it has little effect on under-five mortality rates, which makes the U5MR a more robust estimate than the infant mortality rate when data are drawn from household surveys.

There are also gender-based biases in the reporting of child deaths. Moreover, survey frequency is generally only every three to five years.

Another limitation is that indirect estimates rely on model actuarial (“life”) tables that may be inappropriate for the population concerned. Indirect estimates obtained from household surveys have attached confidence intervals that need to be considered when comparing values over time or across countries. Similarly, these estimates are often affected by non-sampling errors that may affect recent levels and trends of U5MRs.

GENDER EQUALITY ISSUES

In settings where there is no gender-based discrimination in the care and treatment of young children, under-five mortality rates are higher for boys than for girls due to biological factors that tend to favour girls, especially in early infancy. The degree of expected female advantage varies according to the overall level of mortality and the profile of causes of death. Thus, equal rates of under-five mortality for boys and girls would actually be considered an indication that girls are suffering disadvantage in survival.

The effects of gender discrimination on child survival become more apparent after early infancy, because nutrition and medical interventions are more important determinants of survival among older infants and young children. Because of the relative weight of neonatal deaths in overall under-five mortality, girls’ advantage in the neonatal period may mask disadvantage in later ages when considering the under-five mortality rate. To better assess gender differences in mortality among children under-five, it is preferable to disaggregate mortality rates by age, considering separately mortality under age one (infant mortality) and at ages 1-4.

Analysis of gender differences in mortality is also complicated by the large degree of sampling error in mortality estimates from sample surveys. Sampling error becomes larger when estimates are disaggregated by sex and it is often quite difficult to assign statistical significance to differentials or trends in under-five mortality by sex. This should be taken carefully into account before drawing comparisons between published estimates from different surveys. Vital registration, even if not complete, may also give valuable information on relative gender differentials if it can be assumed that gender bias in the reporting of births and deaths is not large. In countries or subpopulations with small numbers of deaths, estimates of differentials based on vital registration may fluctuate considerably from year to year.

DATA FOR GLOBAL AND REGIONAL MONITORING

The United Nations Children’s Fund (UNICEF), the World Health Organization (WHO), and the United Nations Population Division (UNPD) produce country estimates based on available national data for purposes of international comparisons and assessment of global and regional trends. Data series produced by the different agencies may differ owing to differences in methodologies used to estimate data and differences in reporting periods.

Current estimates of U5MR are generally based on empirical data from several or even many years before. Vital registration data are available on a yearly basis but are often published at the country level with a lag of 2 or more years. Population censuses are conducted every ten years and results are published one to three years after the census. Household surveys, such as DHS and MICS, are in general implemented every three to five years with results published within a year of field data collection. On average, the most recent U5MR estimates from household surveys refer to 2.5 years before the time of the survey or 3.5 years before the time of publication of findings.

Different data sources and calculation methods often yield widely different estimates of child mortality for a given time and place. In order to reconcile these differences, UNICEF developed, in coordination with WHO, the World Bank and UNPD, an estimation methodology that minimizes the errors embodied in each estimate and maximises the consistency of trends over time. These estimates are not necessarily recognized as the official U5MR country level estimates. However they allow comparisons to be made between countries, despite the varied numbers and types of country level data sources.

To seek out national data sources that might be overlooked, UNICEF conducts an annual exercise called the Country Reports on Indicators for the Goals (CRING). CRING gathers recent information for all indicators regularly reported by UNICEF, including the infant and under-five mortality rates.

After plotting all available values for infant and under-five mortality, analysts use weighted least squares models to fit a multi-spline regression line to the data points and extrapolate the trend to the present. The use of weights allows analysts to judge the relative quality of each data set and determine how representative each set is of the population. Analysts then decide which set of estimates (infant mortality rates or under-five mortality rates) are more consistent and use a model life table to derive the other set of estimates from it.

Global figures produced by the inter-agency group for child mortality estimation may differ from those produced at the country level for different reasons. Global estimates use all available data obtained from different sources (vital registration, census, and household surveys) to produce estimates that represent trends and levels of child mortality in the countries. On the other hand, country estimates are obtained from just one source (normally household surveys such as the DHS), a combination of data sources, or from using different estimation methods.

Inter-agency group estimates are updated annually. U5MR estimates are produced and presented at the regional and global levels only if data are available for at least 50 per cent of the region or the total population of the countries considered.

SUPPLEMENTARY INFORMATION



EXAMPLES



REFERENCES

United Nations (2001). Principles and Recommendations for a Vital Statistics System, Revision 2. New York. Available from http://unstats.un.org/unsd/pubs/gesgrid.asp?id=264.

United Nations (2008). World Population Prospects: The 2008 Revision. New York. Available from http://esa.un.org/unpp/.

United Nations Children’s Fund (2006). Multiple Indicator Cluster Survey Manual 2005. Monitoring the Situation of Children and Women. New York. Available from http://www.childinfo.org/mics3_manual.html.

United Nations Children’s Fund, World Health Organization, World Bank and United Nations Population Division (2007). Levels and Trends of Child Mortality in 2006: Estimates developed by the Inter-agency Group for Child Mortality Estimation. New York. Available from http://www.childinfo.org/files/infant_child_mortality_2006.pdf.

World Health Organization. WHO Statistical Information System (WHOSIS). Internet site http://www.who.int/whosis.

World Health Organization (2009). International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10). Geneva. Available from http://www.who.int/classifications/icd.

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