title: The British retrospective and prospective studies.
abstract: The clinician needs scientific evidence to enable him to advise patients efficiently and correctly. The sources of this evidence are listed and the part played by each discussed. The rarity of adverse effects from the use of oral contraceptive pills entails the need to make use of epidemiologic studies. The different types of study are briefly described, with examples from recent work carried out in Britain. The advantages and problems of interpretation associated with each are discussed. The present position taken by United Kingdom doctors working in the field of contraceptive practice is summarized.
mesh_terms: D003276:Contraceptives, Oral / Q000009:adverse effects; D003280:Contraceptives, Oral, Synthetic / Q000009:adverse effects; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D011247:Pregnancy; D011446:Prospective Studies; D012107:Research Design; D012189:Retrospective Studies; D012306:Risk; D006113:United Kingdom
chemical_list: D003276:Contraceptives, Oral; D003280:Contraceptives, Oral, Synthetic