Incidence of Ectopic Pregnancy in Rochester, Minnesota, 1950–1981

Trends in the occurrence of ectopic pregnancy from 1950 through 1981 were evaluated in the defined population of Rochester, Minnesota. The average ratio of ectopic pregnancies to live births was 1:171. The ratio declined from 1:141 to 1:217 from 1955–1959 to 1970–1974 and increased sharply to 1:122 by 1975–1980. Similarly, the average age-adjusted incidence rate of ectopic pregnancies per 100,000 women of childbearing age was 49 over the period studied. A peak rate of 79 per 100,000 was reached in 1955 to 1959, and a trough of 30 per 100,000 occurred in 1970 to 1974; this was followed by a sharp increase to 49 per 100,000 in 1975 to 1981. Methods of measuring ectopic pregnancy are contrasted, and possible risk factors are suggested.