Reversible anti-fertility effect by non-occluding oviductal copper coils in the rabbit

Placement of two 1 cm copper (Cu) coils around the mid-region of each oviduct in a group of five female rabbits with proven fertility, 34 days before mating, virtually prevented fetal implantation in these animals. The oviducts remained patent during a 47 day implantation period and following removal of the Cu coils, does that were remated became pregnant. In two of these does an implantation rate (living fetuses/corpora lutea) of 33% (7/21) was observed and one post-Cu implanted doe had a litter of two. Among four does bearing a single Cu coil on their left oviduct for 28 days prior to mating there was 19% (4/21) implantation of the left side and 56.3% (9/16) on the untreated right side, suggesting a local action by the metal. The results indicate that Cu is an effective anti-fertility agent when implanted around the oviducts and, as a corollary, it is apparent that the metal is not restricted to placement in the uterus in order to prevent pregnancy in rabbits. Non-occluding Cu containing devices may offer a new approach to reversible fertility control in the female that merits further investigation.