title: Epidemiology on trial.
authors.forename: Willem
authors.initials: W
authors.lastname: de Laat
authors.forename: Werner Karl
authors.initials: WK
authors.lastname: Raff
mesh_terms: D015982:Bias; D003277:Contraceptives, Oral, Combined / Q000009:adverse effects*; D006801:Humans; D007603:Jurisprudence; D013923:Thromboembolism / Q000139:chemically induced*; D006113:United Kingdom; D020246:Venous Thrombosis / Q000139:chemically induced*
chemical_list: D003277:Contraceptives, Oral, Combined