1968～74年,英格兰和苏格兰的17所计划生育诊所观察了17032例25～39岁,用口服避孕药或阴道隔膜,IUD 避孕至少5个月的白种已婚妇女。通过门诊或发信、电询、登门对她们进行随诊。每年除移居或死亡外的失访率为0.3%。随诊期间由研究助手整理每个妇女的妊娠及其结局详细情况,避孕方法的变化,涂片检查结果,转院门诊或住院原 From 1968 to 1974, 17 family planning clinics in England and Scotland looked at 17032 white married women aged 25-39 years with oral contraceptives or vaginal septum who contracted IUD for at least 5 months. Through the clinic or send a letter, call, door to their follow-up. The annual loss rate except for immigration or death is 0.3%. Details of pregnancies and their outcomes for each woman, change in contraceptive methods, smear test results, referral clinic or hospitalization by Research Assistants during follow-up