Incidence of pelvic inflammatory disease in clinical trials with Cu-7 (intrauterine copper contraceptive): a statistical analysis.

Pelvic inflammatory disease (PID) was recorded for 365 of 10,760 women using the Cu-7 for up to 48 months during clinical investigations in the United States. This involved a total exposure of 242,169 woman-months, or some 20,000 woman-years. The overall incidence of PID was 18 cases/1000 woman-years. Incidence was inversely related to age and to duration of use. It was statistically significantly greater in parous subjects than in nulliparous, after stratifying for age. The estimated rates in this study do not differ markedly from those in most other prospective investigations.