title: Oral contraceptives and rheumatoid arthritis. Bias in observational studies of cause-effect relationships.
authors: T D
authors: TD
authors: Spector
authors: A J
authors: AJ
authors: Silman
mesh_terms: D001172:Arthritis, Rheumatoid / Q000139:chemically induced*; D003276:Contraceptives, Oral / Q000009:adverse effects*; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans
chemical_list: D003276:Contraceptives, Oral