Incidence of uncomplicated genital infections in women using oral contraception or an intrauterine device: a prospective study

Over a period of 2 years, the authors prospectively followed a cohort of 123 women using an intrauterine device (IUD) and 108 women using oral contraception (OC) in one family practice. They found nine new episodes of cervical chlamydial infection in OC users (7/100 Woman years (WY)) as compared to 1 new episode in IUD users (0.8/100 WY), yielding a relative risk (RR) for OC users of 8.8 (95% confidence interval (CI): 1.3-59.0). During the 24 months of observation, 15% of OC and 2% of IUD users acquired at least one episode of Chlamydia trachomatis infection (P= .01). Bacterial vaginosis occurred more frequently in IUD users (25/100 WY) than in OC users (9/100 WY) (RR = 2.8; 95% CI: 1.5-5.1). During the 24-month period, 50% of women using an IUD had at least one episode of bacterial vaginosis, compared with 20% of the OC users (P= .001). Symptomatic bacterial vaginosis was associated with the use of an IUD (RR for IUD users was 7.7; 95% CI: 2.1-28.4), whereas asymptomatic bacterial vaginosis was associated with sexual promiscuity.