The demographic transition.
Demographic transition is a set of changes in reproductive behavior that are experienced as a society is transformed from a traditional pre-industrial state to a highly developed, modernized structure.  The transformation is the substitution of slow growth achieved with low fertility and mortality for slow growth maintained with relatively high fertility and mortality rates.  Contrary to early descriptions of the transition, fertility in pre-modern societies was well below the maximum that might be attained.  However, it was kept at moderate levels by customs (such as late marriage or prolonged breastfeeding) not related to the number of children already born.  Fertility has been reduced during the demographic transition by the adoption of contraception as a deliberate means of avoiding additional births.  An extensive study of the transition in Europe shows the absence of a simple link of fertility with education, proportion urban, infant mortality and other aspects of development.  It also suggests the importance of such cultural factors as common customs associated with a common language, and the strength of religious traditions.  Sufficient modernization nevertheless seems always to bring the transition to low fertility and mortality.
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D001723:Birth Rate; D003267:Contraception; D003710:Demography; D019049:Developed Countries; D003906:Developing Countries; D004467:Economics; D004522:Educational Status; D005060:Europe; D005193:Family Planning Services; D005298:Fertility; D007226:Infant Mortality; D007774:Lactation; D008393:Marriage; D009026:Mortality; D010298:Parity; D011153:Population; D011154:Population Characteristics; D011157:Population Dynamics; D012106:Research; D012107:Research Design; D012922:Social Change; D012939:Social Planning; D012942:Social Sciences
Birth Rate; Contraception; Demographic Factors; Demographic Transition; Demography; Developed Countries; Developing Countries; Development Planning; Economic Development; Economic Factors; Educational Status; Europe; Family Planning; Family Planning, Behavioral Methods; Fertility; Fertility Measurements; Fertility Rate; Infant Mortality; Lactation, Prolonged; Macroeconomic Factors; Marriage; Marriage Patterns; Measurement; Mortality; Nuptiality; Parity; Population; Population Characteristics; Population Dynamics; Population Theory; Research Methodology; Social Change; Social Development; Social Sciences; Total Fertility Rate