Population 18 History 13 Social conditions 9 Fertility, Human 8 Families 6 Demography 5 Family members 5 Family size 5 Women 5 Demographic transition 4 Emigration and immigration 4 Marriage 4 Social Sciences 4 Social aspects 4 Social sciences 4 Birth control 3 Family demography 3 Living arrangements 3 Older people 3 Public Health 3 Public health 3 Statistics 3 Statistics for Social Science, Behavorial Science, Education, Public Policy, and Law 3 Academic achievement 2 Aging 2 Birth order 2 Contraception 2 Cost and standard of living 2 Demographic anthropology 2 Developing countries 2