title: Correspondence (letter to the editor): weaknesses in study design.
authors.forename: Eiko E
authors.initials: EE
authors.lastname: Petersen
mesh_terms: D059026:Diagnostic Self Evaluation; D005260:Female; D006801:Humans; D007752:Obstetric Labor, Premature / Q000209:etiology* / Q000517:prevention & control*; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D047928:Premature Birth / Q000517:prevention & control*; D016585:Vaginosis, Bacterial / Q000175:diagnosis* / Q000517:prevention & control*