A multicentre comparative clinical study of CLa implant and Sino-implant was carried out at 100 subcentres in 11 provinces, and a total of 19673 subjects were recruited. Two year follow up has been finished. The follow-up rate at the end of two years was 94,29%. Two-year cumulative continuation rate per 100 women for Sino-implant(89.93) was significantly higher than that for CLa implant (88.89). Two-year cumulative pregnancy rates per 100 women were 0.0462(CLa implant) and 0.281(Sino-implant) respectively; there was statistically significant difference between them. No ectopic pregnancy was recorded among CLa implant users and three ectopic pregnancies were reported among Sino implant users,resulting in an ectopic pregnancy rate of 0.163 per 1000 women years. The incidence of side-effects appeared to diminish with time. The major side effects were the menstrual disturbances, which accounted for more than 90% of the total sideeffects, and the incidence of frequent menstruation, irregular bleeding and spotring was higher than that of infrequentjscanty menstruation and amenorrhea. Use of CLa implant had higher incidence of amenorrhea and infrequentjscanty menstruation than that of Sin-imptant. During two-year follow-up, the number of discontinuation due to menstrual problems contributed 78% of the total number of discontinuation; two year menstrual-related cumulative discontinuation rates were 8.96 per 100 women for CLa implant and 7.84 for Sino-implant; there was statistically significant difference(P< 0.01). Two-year study shows that the two types of implant are similar to Norplant in the incidence of side-effects and contraceptive efficacy as well as two year continuation rates.
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