Adolescents Age Factors Americas Behavior Clinic Activities Contraception Contraceptive Agents Contraceptive Agents, Female Contraceptive Methods Counseling Delivery Of Health Care Demographic Factors Developed Countries Developing Countries Distributional Activities Family Planning Family Planning Personnel Family Planning Programs Health Health Personnel North America Northern America Oral Contraceptives Organization And Administration Physicians Population Population Characteristics Premarital Sex Behavior Prescriptions Program Activities Programs Research Methodology Sampling Studies Sex Behavior Studies Surveys United States Youth