Socio-demographic determinants of intrauterine device use and failure in China.

BACKGROUND: This study examines social, demographic and family planning programme factors influencing intrauterine device (IUD) use, failure and subsequent resolution ('use dynamics') in the 1988 Chinese National Survey of Fertility and Contraceptive Prevalence. METHOD: A time-to-failure model was used to identify independent determinants of IUD failure. Logistic regression was used to identify independent predictors of abortion in women after failure. RESULTS: Being younger at IUD fitting [<25 versus > or = 35 years, hazard ratio 5.9, 95% confidence interval (CI) 4.3, 7.7] and having a larger number of living children (> or = 3 versus <2 children, hazard ratio 1.2, 95% CI 1.1, 1.4) predict higher risk of IUD failure when controlled for each other; but in women with IUD failure, being older and having fewer children predict a much higher chance of resulting abortion. Contraceptive history and social/regional factors were also associated with higher IUD failure risk, in particular, use before 1984 (hazard ratio 1.3, 95% CI 1.2,1.4); and some of these factors were also predictive of abortion following failure. CONCLUSIONS: The determinants of IUD use dynamics suggest two main possible mechanisms. Some determinants may reflect effects of the Chinese family planning programme; some may indicate women's physiological and biological reactions to IUD. Health implications and relevant policy recommendations are discussed.