Oral Contraceptives and Chlamydia Infections

To the Editor.— Before conclusions are drawn that oral contraceptives (OCs) do not protect against pelvic infections (PID) caused byChlamydia trachomatis,1a somewhat more critical examination of the literature may be in order. The highest incidence of chlamydial infection has been shown to occur in women younger than 25 years2,3; the highest percentage of women using OCs is also in this age group.3,4Chlamydial infection is more common in single and divorced women than in married women,2,3,5in women whose partners have experienced recent nonspecific urethritis,5and is also associated with having more than one sex partner2and with nulliparity.2,3 There is no correction for the effects of these apparent risk factors in any of the case-control studies cited by Washington et al1in which OC use has been associated with increased incidence of chlamydial infection. It is difficult to know