Copper T IUD use and ectopic pregnancy rates in the United States

Over a four-year exposure period, the rate of ectopic pregnancy for women using a Copper T IUD was less than 1 per 1000 years of use. The cumulative 4-year probability of having an ectopic pregnancy while using the Copper T was 4 per 1000 women. These results are based on a study of 35,496 women with 38,064 years of use. Data on ectopic pregnancies in the United States provide a basis with which IUD experience may be compared. The National Hospital Discharge Survey shows a doubling in the number of ectopic pregnancies and in the incidence rates between 1965 and 1976. The relative risk of ectopic pregnancy among IUD users as compared with sexually active women not using the pill or sterilization may have been above 1 in 1965. In 1976, the relative risk is estimated to have been below 1. Compared with all woman-years of exposure, including women using contraceptive sterilization and the pill, the relative risk of extopic pregnancy to IUD users in 1976 was about 1. The IUD could not have been a major factor contributing to the recent doubling in the rate of ectopic pregnancy in the U.S.