Discontinued use of intrauterine contraceptive device and pregnancy loss.

To evaluate the risk of spontaneous abortion among former intrauterine contraceptive device (IUD) users, we compared the contraceptive history of 328 women with a spontaneous abortion up to 28 weeks' gestation with that of 1715 women having a term delivery. A similar percentage of case and comparison subjects reported prior IUD use as well as IUD use within the year before pregnancy. However, IUD use lasting more than 12 months was associated with a 1.5-fold increase in the crude risk of spontaneous abortion up to 28 weeks' gestation (p less than 0.05), a 1.8-fold increased risk of first-trimester spontaneous abortion, and a 1.7-fold increased risk of incomplete abortion (p less than 0.01). The results were not altered by control of individual confounding factors. When confounding factors were controlled simultaneously in a multiple logistic regression analysis, the relative risks were 1.4, 1.7 and 1.6, respectively; however, they were no longer statistically significant. The results suggest that prolonged IUD use may be associated with a modest increase in risk of subsequent spontaneous abortion.