Ectopic pregnancy. Relationship to the preceding contraception.

The incidence of extrauterine pregnancies in all the deliveries in this clinic has increased from 1.3% in 1968 to 2.5% in 1976. Of 163 consecutive extrauterine pregnancies during a ten month period in 1976, 40% had an intrauterine contraceptive device in situ at the time of conception. 650 healthy women who had had an IUD inserted in 1973 were follow-up for an average of 3 years and all extrauterine and intrauterine pregnanices registered while the device was in situ. 27 intrauterine and 4 extrauterine pregnancies occurred over 1,572 women-years of use. From these data it was calculated that 99.5% of all possible intrauterine implantation and 93.5% of tubal implantations were inhibited by the device. This difference is apparently the reason for the increased risk of extrauterine pregnancies in IUCD users.