IUD use and the risk of ectopic pregnancy: a meta-analysis of case-control studies.

Because of inconsistent findings among case-control studies on the relationship between IUD use and the risk of ectopic pregnancy, a meta-analysis of published literature was conducted. From 1977 through 1994, 19 publications regarding 16 studies of ectopic pregnancy and IUD use were found by MEDLINE and manual search. The odds ratio (ORs) of ectopic pregnancy with current and past IUD use in each study were pooled. A quality score system was developed to assess each study. Funnel plot was used to assess potential publication biases. For current IUD use, when cases were compared to pregnant controls, there was an increased risk of ectopic pregnancy (pooled OR: 10.63, 95% confidence interval (CI): 7.66-14.74); when cases were compared to non-pregnant controls, there was no risk of ectopic pregnancy (pooled OR: 1.06, 95% CI: 0.91-1.24). Past IUD use could mildly increase the risk of ectopic pregnancy (pooled OR: 1.40, 95% CI: 1.23-1.59). Selecting pregnant or non-pregnant women as controls, however, did not affect the OR estimates of past IUD use. Current IUD use does not increase the risk of the ectopic pregnancy. However, a pregnancy with an IUD in situ is more often an ectopic one than a pregnancy with no IUD. Past IUD use could mildly elevate the risk of ectopic pregnancy.