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[A retrospective epidemiological investigation of the contraceptive efficacy of IUDS].


 This retrospective, epidemiological study was conducted in 6 townships of a Shanghai suburb in China between 1978-82 to investigate the 1st insertion of the stainless steel ring (Type O) and Silicon copper V-shaped devices (Type V). The total number of cases investigated were 3264. Results showed that the expulsion and pregnancy rates with Type V were significantly lower than that of Type O; however, removal rates for bleeding and pain with this method were significantly higher than for the Type O. The difference appeared mainly within the 2-3 years after insertion. After that time, the contraceptive efficacy of the 2 IUDs appear to be approximately the same. Reasonable shape and material of the Type V were very important factors in improving contraceptive efficacy. Age, parity, and time of insertion affected only the expulsion rate of the Type O, but not the Type V. Physical labor appears to have the potential for increasing the expulsion frequency of Type O; age was also an important factor for this type. Women over age 26 had lower expulsion rates than those under 26 and expulsion rates for this method decreased gradually with an increase in age. Multiple parity and postabortion might also lead to decreased expulsion rates. (author's modified)
