Journal Article 716 Behavior 253 Developing Countries 179 Population 159 Demographic Factors 154 Asia 122 Economic Factors 114 mehr ... Population Dynamics 112 Family Planning 110 Psychological Factors 101 Population Characteristics 89 Developed Countries 80 Health 79 Diseases 73 Americas 71 Research Methodology 70 Contraception 69 Fertility 67 Organization And Administration 67 Research Support, Non-U.S. Gov't 67 behavior 65 Age Factors 64 North America 62 Programs 59 Reproductive Behavior 59 Socioeconomic Factors 59 Education 56 Viral Diseases 55 Sex Behavior 52 Youth 52 weniger ...