Age structure. The distribution of a population according to age, usually by 5 - year age groups. Age-specific fertility rate. The number of births during a year to women in a particular age group , usually per 1,000 women in a 5 - year age group a t midyear. Aging. An increase in the proportion of the populat ion in the older ages. May also be measured as an increa se in the median age of the population. AIDS. Acquired immune deficiency syndrome. Base population. The population, usually by age and sex, for the initial year of a projection . Birth rate. The average annual number of births during a year per 1,000 population at midyear . Also known as the crude birth rate. Children ever born. The total number of births a woman has had, regardless of whether the children are living or dead at the time of the inquiry. Children surviving. The number of children a woman has had that are still living at the time of th e inquiry. Cohort. A group of individuals born in the same calendar year or group of years. Cohort component method. See component method. Component method. A method of estimating or projecting a population in which separate components of populat ion change (fertility, mortality, and migration ) are used to derive the total population. When such pro jections are made also by age and sex, the proc edure is known as the cohort component method. Components of change. Fertility, mortality , and migration. Contraception. The conscious effort of couples to regulate the number and spacing of births. Also known as family planning. Contraceptive prevalence rate. The percent of curre ntly married women of reproductive age (normally defined as the range 15 to 49 years) who use contraception. Crude birth rate. See birth rate. Crude death rate. See death rate. Currently married women. Women ages 15 to 49 e ither formally married or living in union with a man (consensual unions). Same as "married women of reproduc tive age." Death rate. The average annual number of deaths during a year per 1,000 population at midyear . Also known as the crude death rate. Development category. The classification of regions into "less developed" and "more developed" according to their general level of economic development. In this re port, countries are classified according to the grouping used by the United Nations. See references to these terms in the Glossary for details. DHS. Demographic and Health Surveys, an ongoing pro gram of household surveys implemented by Macro Internati onal,Inc. and collaborating organizations. Family planning. See contraception.Growth rate . The average annual percent change in the population, r esulting from a surplus (or deficit) of births over deaths and the balance of migrants enterin g and leaving a country. The rate may be positive or neg ative. Also known as population growth rate or average annual rate of growth. HIV. Human immunodeficiency virus. The virus t hat causes AIDS. Indirect estimation. The use of special techniques< /NP> to estimate demographic measures (such as fertility and mortality) when information is not adequate for mea suring them directly. Infant mortality rate. The number of deaths of infants under 1 year of age from a cohort< /NP> of 1,000 live births. Denoted 1 q 0 or IMR, it is the probability of dying between bi rth and exact age 1. IUD. Intrauterine device, a method of cont raception. iwgAIDS. Interagency Working Group on AIDS. Less developed countries. The "less developed" countries include all of Africa, all of Asia except Japan, the Transcaucasian and Central Asian republics of the NIS, all of Latin America and the Caribbean, and all of Oceania except Australia and New Zealand< /NP>. This category matches the "less developed country" classification employed by the United Nations. "Less de veloped" countries are also referred to in the report as "developing" countries. Life expectancy at birth. The average number o f years a group of people born in the same year can be expected to live if mortality at each age remains constant in the future. Life table. A statistical table that follows a hypo thetical cohort of 100,000 persons born at the same time as they progress through successive ages, with the cohort reduced from one age to the next according to a set of death rates rates age age all all persons die. Married Married women reproductive reproductive ageMWRA MWRA. Women Women ages 15 49 49 formally marrie d or living in union union a a manconsensual consens ual unions. Same as "currently currently married women" Median Median age The The midpoint age separates the the younger half a a population the the older half Modern Modern methods contraception. contraception, Condoms, injectables's, IUD 's pills vaginal methodsspermicides, spermicides, diaphragms capscaps, and voluntary voluntary sterilization a a woman her her. partner developed countries. countries "more developed" countries countries areas areas all all of North Am erica Europe Europeincluding the the Baltics the the four European republics the the NIS plus Japan, Ja pan, Australia NewNew Zealand This This categor y the "more developed" classification classification by the the United Nations Natural Natural increase The The difference the the number births births the the number deaths. deaths Net migration rate The The difference t he the number migrants migrants and those those leav ing a country a a year per 1,000 midyear midyea r population May also be expressed in percent. percent A positive figure known as a a net immigration rate a a n egative figure a a net emigration rate New New Independent StatesNISNIS. Fifteen Fifteen n ations from the the former Soviet Union The The Commonwe alth IndependentIndependent StatesCISCIS refers to these these countries the the three Baltic nations Latvi a, Latvia, Estonia Lithuania. Lithuania. Pandemic A global epidemic Projections. Projections Data population population vital vital rates for future future years on stati stics statistics population population censuses vital vital registration systems or sample sample surveys to the the recent past and on assumptions assumptions future < NP>future trends Rate Rate natural natural increase The The differen ce the the crude birth rate the the crude death rate Replacement Replacement level fertility The The average numb er children children each woman have to bear for a a population remain the the same size the the long t erm Conventionally taken to be an an average 2.1 2.1 chi ldren woman. woman. Seroprevalence The percent a a popu lation testing positive infection infection a a blood te st In the the context this this report the the percent testing positive antibodies antibodies HIV. HIV Sustainable development The The term to ac hieving economic economic and social development ways ways do not exhaust a a country 's natural resources See, also, Ashford Ashford1995) and The World The World Commission and Environment (1987Development. In the Commissio n's words. the Commission 's words ... sustainable d evelopment a process change change which the th e exploitation resources, resources the direction i nvestments, investments the orientation technological technological development and institutional institutional chang e made consistent with the the future well as present pr esent needs (Ibid. Ibid9. Total Total fertility rate The The average number child ren children would be born per woman woman all all w omen to the the end their their childbearing ye ars bore children children to a given set set age-s pecific age-specific fertility rates Traditional Traditional methods contraception. contraception Periodic abstinence rhythm, rhythm, withdrawal , douche folk folk methods Also known as natural natural methods Under-- 5 mortality Number Number deaths deaths children children 5 5 years age age a a c ohort 1,000 live births. births Denoted 5q0 it it the the probability dying between birth birth ex act exact age 5 Underenumeration. Underenumeration a a census the t he erroneous counting fewer fewer persons a a population actually belong to it. it. Underregistration a a vital registration system the the failure register all all vital events occu r in a a population Unmet Unmet need family family planning Nonuse Nonu se contraception contraception women women would li ke to regulate their their, fertility as the the pro portion currently currently married women reproductive r eproductive age using contraception contraception wishing ei ther to postpone the the next birth birth to prevent unw anted unwanted childbearing having achieved their their number number children. children Vital events Births Births deaths. deaths Vital rates Birth Birth rates death death rates Vital Vital registration The The recording vital vi tal events legal, administrative, and statistical statistical pur poses WHO. World World Health Organization WHO// GPA World World Health Organization / Global Programme on AIDS