The effect of increasing copper on loop A and comparisons with the copper T-200 and loop D-plain.

Preliminary results of a study on the effects of increasing the surface area of copper on the Lippes loop A IUD showed a lower pregnancy rate with increased copper. The participating women (mean age 26) were followed for another 6 months. The effectiveness of loops A-135 (135 square mm surface area of copper) and A-200 (200 square mm) both with horizontal positioning of copper was compared with that of the copper T-200 IUD with vertical positioning of copper. Loop D an IUD without copper served as a control. High positioning of copper in A-200 enabled fundal placement of copper in the uterus. Nonstatistically significant tendencies included: (1) A-200 had more removals for medical reasons (especially bleeding) but a lower expulsion rate than A-135. (2) A-135 had a lower pregnancy rate than A-200. Statistically significant comparisons included: (1) T-200 had a significantly lower expulsion rate than any of the other 3 devices. (2) T-200 had a significantly better continuation rate than A-135 and A-200 but not significantly better than loop D. The fundal positioning of copper with the A-200 device did not improve pregnancy rates.