The effect of a copper intrauterine device during the early stages of pregnancy in the rabbit.

Copper wire intrauterine devices (CuIUD) were surgically inserted into mature female rabbits 15 days prior to artificial insemination. Gold wire intrauterine devices and sham surgery served as controls. Animals were autopsied 48, 72, 96, 120, 144, and 192 hours after artificial insemination. At autopsies performed 48 to 144 hours after insemination, the reproductive tract was flushed and the embryos were examined. At 192 hours, implantation sites were counted and measured. A significant (P less than 0.05) loss of copper from the devices was observed when the devices were weighed after autopsy. The CuIUD had no effect on ovulation, fertilization, or embryo transport up to 120 hours after artificial insemination. The presence of a CuIUD resulted in a slight, but not statistically significant, increase in embryonic degeneration by 120 hours, almost total absence of blastocysts from the uterus by 144 hours, and complete absence of implantation sites 192 hours after insemination. The antifertility effect of a copper intrauterine device appears to occur in the late preimplantation stage of pregnancy in the rabbit.