Objective: To analyze the risk factors for the discontinuation of two types of Norplant implants due to menstrual irregularities during 5-year use among Chinese parous women. Methods: A multi-centre randomized controlled clinical trial was undertaken in eight institutes of China. The data from 14,805 women (7,395 cases of Norplant-I, 7,410 cases of Norplant-II) were analyzed by the methods of life-table and COX Stepwise regression procedure. Results: Menstrual irregularities was the primary factor for discontinuation of implants. The cumulative discontinuation rate after five-year using was 17.00 per 100 women in Norplant-I and 15.26 per 100 women in Norplant-II, respectively. Discontinuation risk due to bleeding seemed to be influenced by educational level, occupation, parity, prior contraceptive use, breastfeeding status, body weight and regions where users lived in. Discontinuation risk for amenorrhea was probably influenced by the type of implant, occupation, parity, breastfeeding status and regions where users lived. Conclusion: Comprehensive counseling and effective treatment are key to reduce the impact of menstrual irregularities and improve the acceptability of the implants.
