title: [Contraceptive effectiveness of sequential preparations].
mesh_terms: D003276:Contraceptives, Oral; D003279:Contraceptives, Oral, Sequential; D005260:Female; D006801:Humans; D011247:Pregnancy
chemical_list: D003276:Contraceptives, Oral; D003279:Contraceptives, Oral, Sequential
vernacular_title: Contraceptieve betrouwbaarheid van sequentiepreparaten