Thema
Age Factors
636
Risk Factors
Biology
620
Demographic Factors
620
Population
620
Population Characteristics
618
Journal Article
617
Diseases
452
Research Methodology
424
Youth
320
Developing Countries
300
Population Dynamics
292
Developed Countries
282
Studies
276
Behavior
221
Family Planning
216
Americas
204
Physiology
204
Research Report
198
Contraception
189
Research Support, Non-U.S. Gov't
188
North America
184
Health
179
Northern America
167
Fertility
166
United States
160
Measurement
159
Viral Diseases
147
Adolescents
138
Mortality
132
Infections
128
Sex Behavior
127
Africa
126
Economic Factors
125
Africa South Of The Sahara
117
Contraceptive Methods
115
Socioeconomic Factors
110
Reproduction
108
Asia
106
Examinations And Diagnoses
100
Infant
98
Neoplasms
98
Europe
97
Fertility Measurements
97
Child
95
Contraceptives, Oral
89
Cancer
85
Research Support, U.S. Gov't, P.H.S.
85
Delivery Of Health Care
83
Parity
77
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